Rhabdoid tumors were first described as a variant of Wilm's tumor, thought to be an unfavorable histologic subtype. It soon became clear that this tumor was sufficiently distinct to be classified on its own. Furthermore, numerous malignancies in nearly all organs have exhibited rhabdoid features leading some investigators to make a distinction between primary rhabdoid tumors and tumors that exhibit rhabdoid differentiation. In any event, it appears the acquisition of the rhabdoid phenotype imparts an aggressive course for the tumor.
GROSS APPEARANCE/
CLINICAL VARIANTS |
CHARACTERIZATION |
| GENERAL |
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Malignant rhabdoid tumors: a clinicopathologic review and conceptual discussion.
Wick MR, Ritter JH, Dehner LP.
Lauren V. Ackerman Laboratory of Surgical Pathology, Washington University Medical Center, St. Louis, MO 63110, USA.
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| Semin Diagn Pathol. 1995 Aug;12(3):233-48. Abstract quote |
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The malignant rhabdoid tumor (MRT) has been a controversial lesion since its seminal description. There is no consensus as to whether it represents a distinctive clinicopathological entity or, alternatively, a phenotypic pattern that is potentially common to several disparate neoplasms. MRT of the kidney is a childhood tumor that is associated with uniformly aggressive behavior, but it shows a wide spectrum of histologic, immunophenotypic, and cytogenetic findings.
Malignant extrarenal rhabdoid tumors (MERTs) have been observed in pure form over a broader range of patient ages and anatomic locations, but they show substantial morphological and biological homology with renal MRT. Lastly, "composite" extrarenal rhabdoid tumors (CERTs)--in which recognizable "parent" neoplasms are admixed with MERTs--also have been recognized in several topographic sites. In aggregate, these observations suggest that "rhabdoid tumors" are a heterogeneous group of lesions with dissimilar lineages of differentiation. Particularly in CERTs, it is likely that the rhabdoid phenotype represents a common end point of clonal evolution in tumors of clearly different origins.
Despite these caveats, the authors do support retention of the diagnosis of "rhabdoid tumor," because the affiliated morphological pattern is uniformly attended by aggressive biological behavior despite potential dissimilarities at a subcellular level.
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The clinicopathologic spectrum of putative extrarenal rhabdoid tumors. An analysis of 42 cases studied with immunohistochemistry or electron microscopy.
Parham DM, Weeks DA, Beckwith JB.
Department of Pathology and Laboratory Medicine, St. Jude Children's Research Hospital, Memphis, TN 38105.
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| Am J Surg Pathol. 1994 Oct;18(10):1010-29. Abstract quote |
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The existence of extrarenal rhabdoid tumor (ERRT) as a discrete pathologic entity has been controversial despite frequent reports of its occurrence.
We performed immunohistochemistry, electron microscopy, or both on 42 cases with this diagnosis sent in consultation to us. Only 12 of the 42 neoplasms had the histological findings of "classic" malignant rhabdoid tumor of the kidney; the remainder displayed a variety of neural, epithelial, myoid, mesenchymal, or ependymal patterns. Electron microscopy also showed that most possessed neural, epithelial, or ependymal features.
Immunohistochemistry generally revealed marked polyphenotypia, with immunoreactivity to a wide array of antibodies against neural, epithelial, glial, and myogenic markers. A specific tissue-based diagnostic category could not be assigned in only 11 of the 42 cases, seven of which lacked material for a comprehensive ultrastructural or immunohistochemical study. We conclude that tumors currently diagnosed as ERRT represent a heterogeneous group of neoplasms that may form unique subsets of known entities within the specific site where they arise or that may defy classification into a specific alternative category.
Our findings lead us to believe that the term ERRT is not valid as representing a specific diagnostic entity and to prefer the term "poorly differentiated neoplasm with rhabdoid features" for undifferentiated tumors.
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| VARIANTS |
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| CENTRAL NERVOUS SYSTEM |
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Primary malignant rhabdoid tumor of the central nervous system - a comprehensive review.
Tekkok IH, Sav A.
Department of Neurosurgery, Mersin University School of Medicine, Zeytinlibahce Caddesi, 33079, Mersin, Turkey
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| J Neurooncol. 2005 Jul;73(3):241-52. Abstract quote |
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This paper presents the case of an eight-year-old girl who presented with headache and vomiting and was found to harbor a right fronto-temporo-parietal, partially cystic and centrally solid tumor that measured 11 x 8 x 7 cm. This vascular tumor was gross totally removed. The initial histopathologic diagnosis was hemangiopericytoma and the patient received a total dose of 5330 cGy of external cranial radiation. Twelve months later, the patient presented with left lower quadrant pain and limping and the spinal MR scans showed metastases at T4-5, T7, T12-L1 and L3 levels. The voluminous lesion at T12-L1 was surgically removed.
Histopathological examination of both specimens revealed that both tumors in fact were malignant rhabdoid tumor (MRT). The patient did not benefit from spinal surgery and died 4 months later. A review of the literature has shown that since Briner et al'. first report in 1985 [Pediatr Pathol 3: 117-118, 1985], 100 MRT cases have been published. More than two-thirds of reviewed cases presented with local recurrence or subarachnoid spread after a mean period of 6.9 months after diagnosis and died two months later. Infratentorial and pineal location and surgery limited to biopsy were poor prognostic indicators. Twenty-two cases remained alive at a mean period of 24.5 months. The longest survival with an intracranial MRT was 65 months. Of those remaining alive, 15 had no evidence of disease (NED).
Our case is the first MRT case immunopositive for HMB-45 and has also shown that the MRT cells grow aggressive over time as demonstrated by a four-fold increase in MIB-1 labeling index.
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Imaging and pathological features of primary malignant rhabdoid tumours of the brain and spine.
Howlett DC, King AP, Jarosz JM, Stewart RA, al-Sarraj ST, Bingham JB, Cox TC.
Department of Radiology, Guy's Hospital, London, UK.
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| Neuroradiology. 1997 Oct;39(10):719-23. Abstract quote |
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In this article two cases of primary malignant extrarenal rhabdoid tumour are described. In the affected children the brain and the spinal cord were the primary sites of origin of the tumour.
The imaging findings are presented and the pathology discussed. Although the imaging features are non-specific, rhabdoid tumour should be included in the differential diagnosis of childhood intracranial and spinal neoplasms.
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Immunohistochemistry of primary central nervous system malignant rhabdoid tumors: report of five cases and review of the literature.
Behring B, Bruck W, Goebel HH, Behnke J, Pekrun A, Christen HJ, Kretzschmar HA.
Institute of Neuropathology, University of Gottingen, Germany.
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| Acta Neuropathol (Berl). 1996;91(6):578-86. Abstract quote |
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Malignant rhabdoid tumors (MRT) are characterized by a typical light microscopic morphology with uniformly round tumor cells, vacuolated cytoplasm with occasional round, hyaline intracytoplasmic, periodic acid-Schiff-positive inclusions, vesicular nuclei with prominent nucleoli and positive immunoreactivity for vimentin. The histogenesis of MRT is controversial.
Five cases of primary central nervous system (CNS) rhabdoid tumors in children are presented. Immunohistochemical, light and electron microscopic features are compared with primary CNS malignant rhabdoid tumors reported in the literature.
Expression of various neurofilaments in our cases of primary CNS rhabdoid tumors was prominent and we therefore favor a neural differentiation of extrarenal intracerebral rhabdoid tumors.
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| GASTROINTESTINAL TRACT |
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Malignant rhabdoid tumor of the colon. Report of a case with molecular analysis.
Marcus VA, Viloria J, Owen D, Tsao MS.
Department of Pathology, Montreal General Hospital, Quebec, Canada.
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| Dis Colon Rectum. 1996 Nov;39(11):1322-6. Abstract quote |
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PURPOSE: Malignant rhabdoid tumors were first described in the kidney as a rare variant of Wilms' tumor with a "rhabdomyosarcomatoid" pattern and a particularly poor prognosis. Further studies have demonstrated these neoplasms as a distinct clinicopathologic entity. Subsequently, tumors with a similar histologic appearance, demonstrating the "rhabdoid" cells, have been found in a variety of extrarenal sites.
METHODS: We report here a case of malignant rhabdoid tumor of the colon studied with selected molecular techniques.
RESULTS AND CONCLUSIONS: This tumor demonstrated several unusual findings for malignant rhabdoid tumors of renal or extrarenal sites, including aneuploidy by flow cytometric analysis and a positive nuclear immunohistochemical staining for p53 protein, which suggests presence of p53 gene mutation. DNA analyses, however, failed to demonstrate the presence of point mutation in any of the ras family genes.
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| INTRATHORACIC |
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Intrathoracic rhabdoid carcinoma: a clinicopathological, immunohistochemical, and ultrastructural study of 6 cases.
Falconieri G, Moran CA, Pizzolitto S, Zidar A, Angione V, Wakely PE Jr.
Department of Pathology, S. Maria della Misericordia General Hospital, Udine, Italy.
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| Ann Diagn Pathol. 2005 Oct;9(5):279-83. Abstract quote |
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We evaluated the clinicopathological spectrum of intrathoracic rhabdoid carcinoma, including its immunophenotype and ultrastructural features.
Our series included 6 cases arising from the lung (4 cases) and the anterior mediastinum (2 cases). The patients were 4 men and 1 woman aged between 40 and 63 years (median, 53 years). Microscopically, all of the lesions were composed of loosely cohesive, large, atypical polygonal cells, with glassy cytoplasms and eccentric nuclei. Chromatin texture was finely granular or open.
On immunohistochemical stain, the neoplastic cells were positive for vimentin in all cases, positive for vimentin, keratins and/or epithelial membrane antigen in all cases, and negative for other antigens. In 1 case, neoplastic cells were also positive for CD34. Electron microscopic study showed prominent perinuclear whorls of densely packed intermediate filaments or mitochondria. All patients were treated with combined chemotherapy and radiotherapy. One patient died 8 months after the diagnosis was made. Of the remaining patients, 3 are alive with evidence of disease progression, including brain metastases.
We concluded that rhabdoid neoplasms arising in the thoracic cavity are aggressive tumors of epithelial lineage and should be categorized as true "rhabdoid carcinomas" instead of being ambiguously designated as "intrathoracic rhabdoid tumors" or "carcinomas with rhabdoid phenotype."
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| LIVER |
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Malignant rhabdoid tumor of the liver. A distinct clinicopathologic entity.
Hunt SJ, Anderson WD.
Department of Pathology, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013.
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| Am J Clin Pathol. 1990 Nov;94(5):645-8. Abstract quote |
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A malignant rhabdoid tumor occurring as a primary hepatic neoplasm in a six-month-old white infant is reported. It was treated by an attempt at total resection involving right hepatic lobectomy and by chemotherapy with cis-platinum, VP-16, and Adriamycin. Despite this, recurrence of the tumor resulted in the girl's death within three months.
The neoplasm showed typical light microscopic features of malignant rhabdoid tumor as well as filamentous cytoplasmic inclusions by electron microscopic examination and staining for both cytokeratin and vimentin by immunohistochemistry.
The classic clinicopathologic features of this tumor support the concept that malignant rhabdoid tumors similar to those of the kidney may occur in extrarenal sites.
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| ORBITAL |
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Congenital orbital and disseminated extrarenal malignant rhabdoid tumor.
Gottlieb C, Nijhawan N, Chorneyko K, O'Grady KF, Harvey JT.
McMaster University School of Medicine, Hamilton, Ontario, Canada.
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| Ophthal Plast Reconstr Surg. 2005 Jan;21(1):76-9. Abstract quote |
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A 5-week premature infant boy with tumorous malformations underwent biopsy of two truncal masses and exenteration of the left orbit. Specimens were examined histologically.
Histologic reports, slides, and clinical photographs were reviewed. A diagnosis of malignant rhabdoid tumor was made. Malignant rhabdoid tumors can present as local or disseminated neoplastic disease involving the orbit and should be considered in the differential diagnosis of rapidly progressing orbital lesions presenting in early infancy.
We review the current classification of rhabdoid tumors and the previous literature on orbital rhabdoid tumors.
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| SKIN |
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Cutaneous extrarenal rhabdoid tumor with myogenic differentiation.
Petitt M, Doeden K, Harris A, Bocklage T.
Department of Pathology, University of New Mexico Health Sciences Center, Albuquerque, NM, USA.
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Background: The rhabdoid phenotype is characterized by large epithelioid cells with abundant eosinophilic cytoplasm and paranuclear inclusions of intermediate filaments. Although originally described in tumors from pediatric kidneys, the rhabdoid phenotype has since been described in a variety of patient ages and extrarenal sites. Extraordinarily, the rhabdoid phenotype has emerged in cutaneous neoplasms, either as a pure extrarenal rhabdoid tumor or a composite phenotype coupled with another malignancy. Regardless of the clinical setting, the rhabdoid phenotype is uniformly associated with aggressive biological behavior. We report the findings from a rare and very aggressive primary extrarenal rhabdoid tumor of the skin with myogenic differentiation.
Case report: A 53-year-old woman presented with an ulcerated nodule on her right medial calf and ipsilateral inguinal lymphadenopathy. Histological examination of the skin nodule as well as cytologic examination of a lymph node disclosed the characteristic rhabdoid phenotype. Electron microscopy demonstrated paranuclear globules of intermediate filaments; special stains suggested an underlying myogenic histogenesis. The patient was aggressively treated with chemotherapy but ultimately died of her disease 8 months after presentation.
Conclusions: The rhabdoid phenotype is rarely seen in cutaneous neoplasms, but when present, portends a poor prognosis adding particular importance to its recognition.
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| SOFT TISSUE |
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Soft-tissue extrarenal rhabdoid tumor with a unique long-term survival.
Fabre A, Eyden B, Ali HH.
Histopathology Department, St Mary's Hospital, London, UK.
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| Ultrastruct Pathol. 2004 Jan-Feb;28(1):49-52. Abstract quote |
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Rhabdoid tumors of kidney and extrarenal rhabdoid tumors are identified by a round-epithelioid cell morphology and a bland immunophenotype, but a distinctive ultrastructure dominated by paranuclear whorls of intermediate filaments, most usually of vimentin.
These tumors are also known to be highly aggressive malignancies, which, typically, bear a poor prognosis, frequently measured in months following initial presentation.
The authors record the case a soft-tissue rhabdoid tumor in a 12-year-old boy with a unique long-term survival in excess of 16 years.
The features of this case are documented, with a brief summary of histological, immunohistochemical, ultrastructural, and genetic characteristics of this entity.
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Extrarenal rhabdoid tumors of soft tissue: a clinicopathologic and immunohistochemical study of 18 cases.
Fanburg-Smith JC, Hengge M, Hengge UR, Smith JS Jr, Miettinen M.
Department of Soft Tissue Pathology, Armed Forces Institute of Pathology, Washington, DC 20306-6000, USA.
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| Ann Diagn Pathol. 1998 Dec;2(6):351-62. Abstract quote |
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Rhabdoid tumor is a well-accepted clincopathologic entity among childhood renal neoplasms; similar tumors have been described in extrarenal locations.
We present the clinicopathologic profile and the immunohistochemical features of a series of soft tissue rhabdoid tumors. Twenty-eight cases coded as extrarenal rhabdoid tumor (ERRT), RT, possible ERRT, and "large cell sarcoma" were retrieved from the Armed Forces Institute of Pathology soft tissue registry. The tumors were reclassified according to strict criteria by light microscopy, clinical information, immunohistochemistry, and, in some cases, electron microscopy.
Soft tissue rhabdoid tumor (STRT) was defined as (1) a tumor composed of noncohesive single cells, clusters, or sheets of large tumor cells with abundant glassy eosinophilic cytoplasm, an eccentric vesicular nucleus, and an extremely large nucleolus; (2) positivity for vimentin and/or cytokeratin or other epithelial markers by immunostaining; and (3) exclusion of other tumor types with rhabdoid inclusions (melanoma, other sarcomas, carcinoma). Eighteen cases met our criteria for soft tissue rhabdoid tumors. The median patient age was 13 years (range, 6 months to 56 years). Ninety-four percent of STRT cases were positive for vimentin and 59% for pan-cytokeratin. Sixty-three percent and 60% were positive for CAM 5.2 and EMA, respectively. Seventy-nine percent stained for at least one epithelial marker; 76% stained for both vimentin and epithelial markers simultaneously. Forty-two percent stained for MSA, and 14% for CEA and SMA. CD99, synaptophysin, CD57 (Leu-7), NSE, and focal S100 protein were identified in 75%, 66%, 56%, 54%, and 31% of the STRT cases, respectively. All STRT cases examined were negative for HMB-45, chromogranin, BER-EP4, desmin, myoglobin, CD34, and GFAP. Follow-up examination in 61% of the STRT patients revealed that 64% of patients died of disease within a median follow-up interval of 19 months (range, 4 months to 5 years); 82% had metastases to lung, lymph nodes, or liver; 22% had local recurrences before metastasis; and 18% were alive without known disease status (median, 5.5 years).
Soft tissue rhabdoid tumor is a highly aggressive sarcoma, predominantly of childhood. Besides having nearly consistent coexpression of vimentin and epithelial markers, STRTs show positivity for multiple neural/neuroectodermal markers that overlap with those of primitive neuroectodermal tumor.
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SPECIAL STAINS/
IMMUNOPEROXIDASE/
OTHER |
CHARACTERIZATION |
| SPECIAL STAINS |
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| IMMUNOPEROXIDASE |
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| GENERAL |
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Immunohistochemical and cytogenetic findings in malignant rhabdoid tumor.
Kaiserling E, Ruck P, Handgretinger R, Leipoldt M, Hipfel R.
Institute of Pathology, University of Tubingen, Germany.
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| Gen Diagn Pathol. 1996 May;141(5-6):327-37. Abstract quote |
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BACKGROUND: The histogenesis of malignant rhabdoid tumor (RT) remains a matter of controversy. From published reports it appears that some extrarenal RT (ERRT) exhibit neural or neuroectodermal features. Systematic investigation of renal RT (RRT) for neural differentiation has not yet been published. In this study, two RRT and two ERRT were investigated by light and electron microscopy, immunocytochemistry, and cytogenetic analysis.
RESULTS: All four cases exhibited similar morphology and a largely consistent immunohistochemical staining profile. Both tumor types showed immunoreactivity for various cytokeratins, epithelial membrane antigen (EMA), vimentin, neurofilaments, S100 protein, neuron specific enolase, Leu7, CD34, p53, MB2, MIC2, VS38c, laminin and fibronectin. Reactivity was usually confined to a small proportion of the tumor cells, especially in the case of antibodies against neurofilaments, NSE, S100 proteins Leu7, CD34 and p53. Only a few of the antibodies (anti-vimentin, MB2, MIC2, anti-EMA, and VS38c) stained the majority of the tumor cells. Chromosome analysis revealed a discrete aberration in 11p (most probably a paracentric inversion in 11p15) in the one RRT investigated. One ERRT had a normal karyotype, but the other one exhibited various structural abnormalities on chromosomes 18 and 22.
CONCLUSIONS: The immunohistochemical investigations revealed many similarities between RRT and ERRT, and all four tumors investigated exhibited neuroectodermal differentiation. As far as histogenetic classification is concerned, our findings point in the direction of the group of tumors that includes Ewing's sarcoma and primitive neuroectodermal tumors.
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| INI1 |
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INI1 expression is retained in composite rhabdoid tumors, including rhabdoid meningiomas.
Perry A, Fuller CE, Judkins AR, Dehner LP, Biegel JA.
1Department of Pathology, Washington University School of Medicine, St Louis, MO, USA.
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| Mod Pathol. 2005 Jul;18(7):951-8 Abstract quote. |
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Rhabdoid cells are encountered in specific entities, such as malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor, as well as in composite rhabdoid tumors derived secondarily from other tumor types. Although rhabdoid tumors are uniformly aggressive, distinction of the entity from the phenotype remains important for its therapeutic implications.
The majority of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors affect infants and young children, harbor chromosome 22q deletions, and inactivate the INI1/hSNF5/BAF47 tumor suppressor gene on 22q11.2. In contrast, most composite rhabdoid tumors are diagnosed in adults, with FISH detectable 22q losses the exception rather than the rule. However, this assay remains limited since 22q dosages are maintained in 20-30% of malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors. Furthermore, chromosome 22 losses are common in some parent tumor types, particularly meningiomas. The recently developed INI1 antibody shows loss of nuclear expression in malignant rhabdoid tumors and atypical teratoid/rhabdoid tumors, though its status in composite rhabdoid tumors is largely unknown.
Therefore, we utilized immunohistochemistry and FISH to study INI1 expression and 22q dosages, respectively, in 40 composite rhabdoid tumors, including 16 meningiomas, 15 carcinomas, three melanomas, two sarcomas, two glioblastomas, and 1 neuroblastoma. Approximately 70% of rhabdoid meningiomas had a 22q deletion, but this was rare in other tumor types. Except for one retroperitoneal leiomyosarcoma, nuclear INI1 expression was retained in all composite rhabdoid tumors, including meningiomas with 22q deletion.
Therefore, we conclude that INI1 immunohistochemistry is a relatively simple, sensitive, and specific technique for distinguishing malignant rhabdoid tumor and atypical teratoid/rhabdoid tumor from composite rhabdoid tumor.
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| ELECTRON MICROSCOPY |
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| DIFFERENTIAL DIAGNOSIS |
KEY DIFFERENTIATING FEATURES |
| ATYPICAL TERATOID/RHABDOID TUMOR |
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| ENDOMETRIAL STROMAL SARCOMA |
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- Endometrial stromal sarcoma with sex cord-like areas and focal rhabdoid differentiation.
McCluggage WG, Date A, Bharucha H, Toner PG.
Institute of Pathology, Royal Group of Hospitals Trust, Belfast, Northern Ireland.
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| Histopathology. 1996 Oct;29(4):369-74. Abstract quote |
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An unusual uterine lesion is described in a patient with postmenopausal bleeding. Grossly, a yellow, polypoid mass projected into the uterine cavity.
Histological examination showed a distinct biphasic pattern with areas of typical low-grade endometrial stromal sarcoma and areas where tumour cells were arranged in cords and trabeculae, resulting in a sex cord-like pattern. In these areas the cells assumed a rhabdoid morphology with eccentric vesicular nuclei, prominent nucleoli and eosinophilic hyaline cytoplasmic inclusions.
Immunohistochemistry showed positive cytoplasmic staining of both components for vimentin, desmin and the cytokeratin marker CAM 5.2, but no staining for CEA and EMA. Electronmicroscopy revealed prominent paranuclear arrays of intermediate filaments. This is the second reported case of endometrial stromal sarcoma with rhabdoid differentiation and the first documented example of rhabdoid cells in sex cord-like areas. The report adds to the list of diverse neoplasms which may display a characteristic rhabdoid morphology and supports the hypothesis that extrarenal rhabdoid tumours are not a distinct clinicopathological entity.
A diagnosis of malignant rhabdoid tumour of the uterus should be considered only when extensive sampling fails to disclose areas with an appearance typical of an endometrial stromal lesion.
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| EPITHELIOID SARCOMA, PROXIMAL TYPE |
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"Proximal-type" epithelioid sarcoma, a distinctive aggressive neoplasm showing rhabdoid features. Clinicopathologic, immunohistochemical, and ultrastructural study of a series.
Guillou L, Wadden C, Coindre JM, Krausz T, Fletcher CD.
Institut Universitaire de Pathologie, Lausanne, Switzerland.
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| Am J Surg Pathol. 1997 Feb;21(2):130-46. Abstract quote |
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Eighteen examples of an unusual malignant soft-tissue neoplasm, the morphology of which ranged from that of "atypical" epithelioid sarcoma to that of a rhabdoid tumor or undifferentiated carcinoma (with transitional forms) are described.
Patients included 11 males and seven females; their median age was 35.5 years with most patients aged 20 to 40 years. Development of a mass was the main presenting symptom. Six tumors developed in the pelvis and perineal region, four in the pubic region and vulva, three in the buttocks, one in the deep soft tissues of the left hip, one on the penis, one in left forearm, one in left axilla, and one on the occiput. Tumor size ranged from 1 to 20 cm (median, 4 cm).
On microscopic examination, the tumor cells invaded the subcutaneous or deep soft tissues, had prominent epithelioid or rhabdoid features, had marked cytologic atypia, and grew in a multinodular pattern in half of the cases. Areas of necrosis were often seen. A granuloma-like pattern reminiscent of that observed in classic epithelioid sarcoma was observed in only two cases.
Immunohistochemically, positivity for cytokeratin, epithelial membrane antigen, and vimentin was seen in all but one of the cases. Of 16 cases, 10 and eight tumors reacted with desmin and CD34, respectively; five of 15 reacted at least focally with smooth-muscle actin, whereas three of 13 and one of 10 reacted for HMB-45 and carcinoembryonic antigen, respectively. S-100 protein and CD31 yielded negative results. Seven tumors were investigated at the ultrastructural level, four of which showed prominent intracytoplasmic intermediate filament aggregates, often accumulating into paranuclear whorls, which is in keeping with the rhabdoid phenotype. Five tumors showed features of epithelial differentiation (i.e., tonofilament-like structures or desmosomes or both), whereas one tumor displayed features of myofibroblastic differentiation. Differential diagnoses include mainly conventional epithelioid sarcoma, extrarenal malignant rhabdoid tumor, epithelioid malignant peripheral nerve sheath tumor, melanoma, rhabdomyosarcoma, and undifferentiated carcinoma. Follow-up information on 14 patients (range, 4 months to 8 years; median, 19 months) revealed local recurrence in one case and metastatic dissemination in six patients, leading to death in five.
In our opinion, the above-described neoplasms represent a usually "proximal-type" of epithelioid sarcoma. In contrast to the conventional, "distal-type" epithelioid sarcoma, the proximal variant is characterized by a predominantly large-cell, epithelioid cytomorphology, marked cytologic atypia, frequent occurrence of rhabdoid features, and lack of a granuloma-like pattern in most cases. It appears to be somewhat more aggressive (or at least metastasizes earlier) than usual epithelioid sarcoma.
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| MELANOMA |
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- Primary malignant melanoma with rhabdoid features: a histologic and immunocytochemical study of three cases.
Borek BT, McKee PH, Freeman JA, Maguire B, Brander WL, Calonje E.
Department of Histopathology, UMDS (St Thomas' Campus), London, UK.
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| Am J Dermatopathol. 1998 Apr;20(2):123-7. Abstract quote |
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Malignant rhabdoid tumors are morphologically characterized by the presence of sheets of large polygonal cells with abundant cytoplasm containing eosinophilic inclusions. They have vesicular nuclei, often with prominent central nucleoli. The term rhabdoid tumor was originally coined to describe a group of rare, aggressive renal neoplasms of childhood. Since then, similar lesions, so-called extrarenal malignant rhabdoid tumors have been increasingly reported.
The evidence to date suggests that, at least in extrarenal locations, rhabdoid tumors do not constitute a homogeneous entity, but rather represent the shared morphological pattern of a diverse range of malignant neoplasms. Although such rhabdoid features are not uncommon in metastatic malignant melanoma, they have only once been briefly described in a primary lesion.
We report three further cases of cutaneous primary malignant melanoma with rhabdoid morphology.
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