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Detailed clinical history and radiologic findings of a patient with hypopituitarism and bitemporal hemianopsia. Surgical interpretation, differential diagnosis, staining results, and final diagnosis of the pituitary lesion.
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Case Study 45 Julia Kofler, M.D.
Question 1 Clinical history: 41 year old male with a 2 year history of progressive hypopituitarism, headache and bitemporal hemianopsia. Describe the lesion on the following CT scan (no MRI images available due to pacemaker).
Question 1 CT with contrast
Answer Diffusely contrast-enhancing suprasellar mass
Question 2 What is your differential diagnosis based on the radiologic appearance and location of the lesion?
Answer • Pituitary adenoma • Craniopharyngioma • Pituicytoma • Granular cell tumor • Meningioma • Pilocytic astrocytoma • Germ cell tumor
Question 3 An endoscopic endonasal resection was performed. An intraoperative consultation was requested. What is your interpretation of the following frozen section and smear preparation? According to the surgeon, the mass extended around the pituitary stalk and appeared highly vascular Click here to view frozen section slide.Click here to view smear preparation.
Answer • Low-grade spindle cell tumor • A pituicytoma was favored over other spindle cell neoplasms
Question 4 Describe the findings on the permanent section. Click here to view slide.
Answer Moderately cellular neoplasm Comprised of mildly pleomorphic spindle cells with variably distinct cell borders, irregular vesicular nuclei and light eosinophilic cytoplasm with a fibrillar quality Cells are arranged in groups and haphazardly interwoven fascicles The fascicles are separated by very thin, compressed vascular channels No mitoses are seen No Rosenthal fibers, eosinophilic granular bodies, Herring bodies or oncocytic change is seen
Question 5 What is your differential diagnosis and which stains may be useful to support your diagnosis?
Answer Pituicytoma, normal infundibulum, pilocytic astrocytoma, spindle cell oncocytoma, granular cell tumor PAS, S100, GFAP, Neurofilament, EMA, Synaptophysin
Question 6 What is your interpretation of the following stains? Click here to view PAS slideClick here to view S100 slideClick here to view GFAP slideClick here to view neurofilament slide
Answer PAS is negative in tumor cells S100 shows strong nuclear and cytoplasmic reactivity GFAP is negative in the tumor cells (may be variably positive in pituicytomas) Neurofilament highlights rare infundibular axons at the margin of the specimen The tumor was also positive for vimentin and negative for synaptophysin and EMA
Question 7 Name a few features that distinguish pituicytoma from normal infundibulum.
Answer Normal infundibular tissue is usually less cellular than a pituicytoma (but cellularity may overlap) Normal tissue is looser in texture and contains axons and perivascular fibrillar zones Normal tissue contains Herring bodies (PAS positive focal axonal swellings) Normal tissue is diffusely positive for synaptophysin and neurofilament; pituicytomas are negative
Question 8 Name a few features that distinguish pituicytoma from pilocytic astrocytoma.
Answer • Pilocytic astrocytomas commonly occur in children, whereas pituicytomas are usually seen in adults • Pituicytomas lack Rosenthal fibers and eosinophilic granular bodies that are commonly seen in pilocytic astrocytomas • Pilocytic astrocytomas usually exhibit a biphasic growth pattern and more variability (compact, piloid, microcystic patterns)
Question 9 Name a few features that distinguish pituicytoma from spindle cell oncocytoma.
Answer • Spindle cell oncocytomas are composed of interlacing fascicles of spindled to epithelioid cells with eosinophilic to oncocytic cytoplasm • Ultrastructurally, numerous mitochondria are seen • Spindle cell oncocytomas are usually positive for vimentin, EMA, S100 and galectin-3 • They are negative for pituitary hormones, GFAP and synaptophysin
Question 10 What is your final diagnosis?
Answer Pituicytoma
Question 11 Name a transcription factor that has recently been shown to be expressed in human fetal and adult pituicytes as well as in a variety of sellar masses (pituicytoma, granular cell tumor, spindle cell oncocytoma)?
Answer Thyroid transcription factor 1, which was also positive in our pituicytoma (see image below) Reference: Lee EB et al. J Neuropath Exp Neurol 2009;68:482