Skin Pseudolymphomas

Background

Pseudolymphomas of the skin mimic lymphomas both clinically and histologically. B-cell pseudolymphomas are recognized as a specific entity while T-cell pseudolymphomas are heterogeneous. Disorders as varied as Jessner's lymphocytic infiltrate, lymphomatoid drug eruptions, lymphomatoid contact dermatitis, lymphomatoid photoallergic reactions including actinic reticuloid, and pseudolymphomatous angiokeratoma (also known as acral pseudolymphomatous angiokeratoma of children or APACHE) have been lumped into this latter T-cell category.

Acral pseudolymphomatous angiokeratoma of children (APACHE)

Actinic reticuloid

Contact dermatitis

Drug eruptions

Jessner's lymphocytic infiltrate

Photoallergic dermatiti

B-cell pseudolymphomas (also known as lymphocytoma cutis, lymphadenosis benigna cutis, cutaneous lymphoplasia, cutaneous lymphoid hyperplasia, and Speigler-Fendt sarcoid) usually present as solitary or grouped nodules, on the head, trunk, and extremities, ranging in size from a few millimeters to 5 cm or more. These lesions may resolve spontaneously after a few months but can recur. The disheartening fact is 25% of these "benign" tumors progress on to lymphomas. The reason may be misdiagnosis of the original lesion or development of lymphoma occurring within this lymphocytic proliferation. Sophisticated studies such as polymerase chain reaction have found monoclonal gene rearrangements in up to 14% of cases. However, monoclonality does not guarantee malignant transformation. Nontheless, distinction from a true lymphoma is the most important task for the pathologist.

Pseudolymphomas have been associated with arthropod bites, drug eruptions, chronic contact dermatitis, tattoos, and injections. Lyme disease in Europe has been associated with these lesions occurring on the ears, areola of nipples, and axillary folds. Other benign conditions that should be excluded include secondary syphilis, lupus profundus, and angiolymphoid hyperplasia with eosinophilia.

The histology is composed of nodular collections of B lymphocytes associated with T lymphocytes, plasma cells, histiocytes, and occasional eosinophils. Unlike malignant lymphomas, the infiltrate usually does not destroy the hair follicles and accompanying structures. There is usually no cytologic atypia or necrosis and a grenz zone is usually present.

TREATMENT AND PROGNOSIS CHARACTERIZATION

PROGNOSIS

CLONALITY

Heavy multinodular cutaneous lymphoid infiltrates: clinicopathologic features and B-cell clonality.

Ceballos KM, Gascoyne RD, Martinka M, Trotter MJ.

Department of Pathology, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, Canada, Department of Pathology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada, and Department of Pathology, Calgary Laboratory Services, University of Calgary, Calgary, Alberta, Canada.
J Cutan Pathol 2002 Mar;29(3):159-167 Abstract quote
BACKGROUND: Criteria for distinguishing between cutaneous lymphoid hyperplasia (CLH) and low-grade B-cell lymphoma are not well defined. We examined the hypothesis that the presence of a clonal B-cell population in heavy multinodular lymphoid infiltrates correlates with clinical presentation and outcome.

METHODS: We identified 29 patients with skin lesions characterized histologically by a heavy dermal lymphocytic infiltrate with a multinodular architecture and extension into deep dermis and subcutaneous fat. Clonality was assessed immunophenotypically by light-chain restriction and also by analysis for IgH-gene rearrangement using PCR on DNA extracted from paraffin blocks.

RESULTS: Follow-up (mean 80 months; median 45 months) was obtained in all patients. Twenty-four patients (83%) presented with a solitary lesion: only four had solitary recurrences, and none developed multiple synchronous lesions or systemic B-cell lymphoma. However, 9/24 of these solitary lesions (38%) were clonal by light-chain restriction or IgH PCR; 5/29 patients (17%) presented with multiple recurrent lesions and continued to develop lesions during the period of follow-up; 3/5 patients (60%) with multiple lesions demonstrated a B-cell clone. No patient developed systemic B-cell lymphoma.

CONCLUSIONS: Heavy, multinodular cutaneous lymphoid infiltrates have an excellent prognosis. Multiple lesions at presentation are the best predictor of recurrent multiple lesions confined to the skin. The presence of a clonal B-cell population does not correlate with clinical presentation or histology, nor does it predict development of further lesions or systemic lymphoma.

Weedon D. Weedon's Skin Pathology. Churchill Livingstone. 1997.

Commonly Used Terms

Follicular-Nodular pattern of lymphocytes present within the dermis.

Grenz zone-Separation of a dermal infiltrate from the overlying epidermis.

Last Updated 5/29/2002

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TREATMENT AND PROGNOSIS	CHARACTERIZATION
PROGNOSIS
CLONALITY
Heavy multinodular cutaneous lymphoid infiltrates: clinicopathologic features and B-cell clonality. Ceballos KM, Gascoyne RD, Martinka M, Trotter MJ. Department of Pathology, Vancouver Hospital and Health Sciences Centre, Vancouver, British Columbia, Canada, Department of Pathology, British Columbia Cancer Agency, Vancouver, British Columbia, Canada, and Department of Pathology, Calgary Laboratory Services, University of Calgary, Calgary, Alberta, Canada.	J Cutan Pathol 2002 Mar;29(3):159-167 Abstract quote BACKGROUND: Criteria for distinguishing between cutaneous lymphoid hyperplasia (CLH) and low-grade B-cell lymphoma are not well defined. We examined the hypothesis that the presence of a clonal B-cell population in heavy multinodular lymphoid infiltrates correlates with clinical presentation and outcome. METHODS: We identified 29 patients with skin lesions characterized histologically by a heavy dermal lymphocytic infiltrate with a multinodular architecture and extension into deep dermis and subcutaneous fat. Clonality was assessed immunophenotypically by light-chain restriction and also by analysis for IgH-gene rearrangement using PCR on DNA extracted from paraffin blocks. RESULTS: Follow-up (mean 80 months; median 45 months) was obtained in all patients. Twenty-four patients (83%) presented with a solitary lesion: only four had solitary recurrences, and none developed multiple synchronous lesions or systemic B-cell lymphoma. However, 9/24 of these solitary lesions (38%) were clonal by light-chain restriction or IgH PCR; 5/29 patients (17%) presented with multiple recurrent lesions and continued to develop lesions during the period of follow-up; 3/5 patients (60%) with multiple lesions demonstrated a B-cell clone. No patient developed systemic B-cell lymphoma. CONCLUSIONS: Heavy, multinodular cutaneous lymphoid infiltrates have an excellent prognosis. Multiple lesions at presentation are the best predictor of recurrent multiple lesions confined to the skin. The presence of a clonal B-cell population does not correlate with clinical presentation or histology, nor does it predict development of further lesions or systemic lymphoma.