Pituicytoma

Background

Pituicytomas are largely noninfiltrative sellar or parasellar tumors of adults. They arise along the distribution of the neurohypophysis, including both the stalk and posterior lobe. They present in the suprasellar space, in the sella, or occupy both.

PATHOGENESIS CHARACTERIZATION

Pituicytes
Functionally specific glial cells that account for the majority of nucleated cells in the neurohypophysis

GFAP-positive, spindle, or stellate cells occupying perivascular zones of the infundibulum and posterior lobe

Ultrastructural studies of basal state show large portions of perivascular basal lamina and cytoplasm engulfs axons and axonal terminations, presumably creating a physical barrier to hormone release.

In physiologic states requiring increased circulating hormone, pituicytes undergo morphologic changes, allowing axonal terminations to contact basal lamina and release hormones into the bloodstream

LABORATORY/RADIOLOGIC/
OTHER TESTS
CHARACTERIZATION

Radiographs

CT scan and MRI Solid, uniformly contrast-enhancing masses
May be cystic

GROSS APPEARANCE/
CLINICAL VARIANTS CHARACTERIZATION

General

VARIANTS

HISTOLOGICAL TYPES CHARACTERIZATION

General
Solid proliferation of elongate spindle cells disposed in interlacing fascicles or storiform arrangement

Abundant, homogeneous, pink cytoplasm devoid of granulation, oncocytic features, or vacuolization

Low grade, featuring only mild nuclear atypia, virtually no mitotic activity, and low MIB-1 labeling indices

Pituicytoma A Distinctive Low-Grade Glioma of the Neurohypophysis

Daniel J. Brat, M.D., Ph.D.; Bernd W. Scheithauer, M.D.; Susan M. Staugaitis, M.D., Ph.D.; Robert N. N. Holtzman, M.D.; Susan Morgello, M.D.; Peter C. Burger, M.D.

From the Departments of Pathology and Laboratory Medicine (D.J.B.), Emory University School of Medicine, Atlanta, GA; the Mayo Clinic (B.W.S.), Rochester, MN; the Cleveland Clinic (S.M.S.), OH; the Department of Neurological Surgery (R.N.N.H.), College of Physicians and Surgeons, Columbia University, New York, NY; the Department of Pathology (S.M.), Mount Sinai Hospital, New York, NY; and the Johns Hopkins Medical Institutions (P.C.B.), Baltimore, MD, U.S.A.

Am J Surg Pathol 2000;24:362-368 Abstract quote

Pituicytoma is a rare, poorly characterized tumor of the sella and suprasellar region that is distinct morphologically from other local tumors and is thought to be derived from neurohypophyseal pituicytes.

Clinical data, neuroimaging studies, and microsections were reviewed from nine such low-grade gliomas.

Immunostains for glial, neuronal, and proliferation markers were performed on all nine tumors and six control neurohypophyses. Three tumors were studied ultrastructurally. Six men and three women, age 30 to 83 years (mean, 48 years), presented with visual symptoms, headache, or hypopituitarism. Magnetic resonance images showed solid, discrete, contrast-enhancing masses, four within the sella and five in the suprasellar space. The tumors consisted of sheets and/or fascicles of plump spindle cells with slightly fibrillar cytoplasm and slightly pleomorphic, oval-to-elongate nuclei with pinpoint nucleoli. Extracellular mucin was prominent in one tumor. Rosenthal fibers, granular bodies, and Herring bodies (granular axonal dilatations characteristic of the normal neurohypophysis) were lacking. Mitoses were rare or absent. MIB-1 labeling indices were low (0.5�2%). Tumor cells were strongly reactive for vimentin and S-100 protein, variably positive for glial fibrillary acidic protein, and nonreactive for synaptophysin and neurofilament protein. Cytoplasm varied in electron density and contained intermediate filaments. Neither meningothelial nor ependymal features were noted. Two tumors recurred at 20 and 26 months after subtotal resection, but none of the six completely resected tumors have done so.

Pituicytomas are discrete, largely noninfiltrative low-grade gliomas of the sellar region that occur in adults. Their histologic appearance is distinct from pilocytic and ordinary, infiltrative astrocytomas. The distinction between pituicytoma and normal neurohypophysis is aided by the latter's content of axons, Herring bodies, and perivascular anucleate zones rich in axonal terminations. Although curable by total excision, subtotal resection can be associated with recurrence.

VARIANTS

DIFFERENTIAL DIAGNOSIS KEY DIFFERENTIATING FEATURES

Pilocytic astrocytomas

Meningiomas

Schwannomas

PROGNOSIS AND TREATMENT CHARACTERIZATION

Treatment 3/9 tumors with infiltrative qualities due to adherence to surrounding normal structures and could not be resected completely.

Liss L, Kahn EA. Pituicytoma. Tumor of the sella turcica: a clinicopathologic study. J Neurosurg 1958;15:481�8.
Jenevein EP. A neurohypophyseal tumor originating from pituicytes. Am J Clin Pathol 1964;41:522�6.

Commonly Used Terms

Brain and Spinal Cord

Last Updated 8/28/2001

LABORATORY/RADIOLOGIC/ OTHER TESTS	CHARACTERIZATION
Radiographs
CT scan and MRI	Solid, uniformly contrast-enhancing masses May be cystic

GROSS APPEARANCE/ CLINICAL VARIANTS	CHARACTERIZATION
General
VARIANTS

HISTOLOGICAL TYPES	CHARACTERIZATION
General	Solid proliferation of elongate spindle cells disposed in interlacing fascicles or storiform arrangement Abundant, homogeneous, pink cytoplasm devoid of granulation, oncocytic features, or vacuolization Low grade, featuring only mild nuclear atypia, virtually no mitotic activity, and low MIB-1 labeling indices
Pituicytoma A Distinctive Low-Grade Glioma of the Neurohypophysis Daniel J. Brat, M.D., Ph.D.; Bernd W. Scheithauer, M.D.; Susan M. Staugaitis, M.D., Ph.D.; Robert N. N. Holtzman, M.D.; Susan Morgello, M.D.; Peter C. Burger, M.D. From the Departments of Pathology and Laboratory Medicine (D.J.B.), Emory University School of Medicine, Atlanta, GA; the Mayo Clinic (B.W.S.), Rochester, MN; the Cleveland Clinic (S.M.S.), OH; the Department of Neurological Surgery (R.N.N.H.), College of Physicians and Surgeons, Columbia University, New York, NY; the Department of Pathology (S.M.), Mount Sinai Hospital, New York, NY; and the Johns Hopkins Medical Institutions (P.C.B.), Baltimore, MD, U.S.A.	Am J Surg Pathol 2000;24:362-368 Abstract quote Pituicytoma is a rare, poorly characterized tumor of the sella and suprasellar region that is distinct morphologically from other local tumors and is thought to be derived from neurohypophyseal pituicytes. Clinical data, neuroimaging studies, and microsections were reviewed from nine such low-grade gliomas. Immunostains for glial, neuronal, and proliferation markers were performed on all nine tumors and six control neurohypophyses. Three tumors were studied ultrastructurally. Six men and three women, age 30 to 83 years (mean, 48 years), presented with visual symptoms, headache, or hypopituitarism. Magnetic resonance images showed solid, discrete, contrast-enhancing masses, four within the sella and five in the suprasellar space. The tumors consisted of sheets and/or fascicles of plump spindle cells with slightly fibrillar cytoplasm and slightly pleomorphic, oval-to-elongate nuclei with pinpoint nucleoli. Extracellular mucin was prominent in one tumor. Rosenthal fibers, granular bodies, and Herring bodies (granular axonal dilatations characteristic of the normal neurohypophysis) were lacking. Mitoses were rare or absent. MIB-1 labeling indices were low (0.5�2%). Tumor cells were strongly reactive for vimentin and S-100 protein, variably positive for glial fibrillary acidic protein, and nonreactive for synaptophysin and neurofilament protein. Cytoplasm varied in electron density and contained intermediate filaments. Neither meningothelial nor ependymal features were noted. Two tumors recurred at 20 and 26 months after subtotal resection, but none of the six completely resected tumors have done so. Pituicytomas are discrete, largely noninfiltrative low-grade gliomas of the sellar region that occur in adults. Their histologic appearance is distinct from pilocytic and ordinary, infiltrative astrocytomas. The distinction between pituicytoma and normal neurohypophysis is aided by the latter's content of axons, Herring bodies, and perivascular anucleate zones rich in axonal terminations. Although curable by total excision, subtotal resection can be associated with recurrence.
VARIANTS

DIFFERENTIAL DIAGNOSIS	KEY DIFFERENTIATING FEATURES
Pilocytic astrocytomas
Meningiomas
Schwannomas

PROGNOSIS AND TREATMENT	CHARACTERIZATION
Treatment	3/9 tumors with infiltrative qualities due to adherence to surrounding normal structures and could not be resected completely.