Intraoperative cytology of pituicytomas

Abstract

Background Pituicytoma is a rare tumor of the sella and suprasellar region. It is common for these tumors to be misdiagnosed radiographically as pituitary adenomas, meningiomas, and craniopharyngiomas. Histologically, pituicytomas are also known to show variable morphology. These factors often complicate intraoperative consultation, especially when tissue is limited. Methods A database search (January 1990‐June 2019) identified 13 surgically resected pituicytomas that were sent for intraoperative consultation. The intraoperative cytology was reviewed by two pathologists, and both squash preparations/smears and touch preparations were included. Results The cytological features of pituicytomas were variable. The cytoplasm ranged from fibrillary to fine and wispy. The nuclei were round to ovoid with occasional tumors showing spindled morphology. Small nucleoli were seen in all tumors, and chromatin was fine to vesicular. While squash preparations were cellular and revealed cohesive groups of tumor cells, touch preparations were often paucicellular with the exception of one tumor. The cytological features of pituicytomas are compared to those of other tumors with similar radiographic appearances. Conclusions Our findings illustrate the range of cytological features of these rare tumors and highlight the difficulty in making a definitive intraoperative diagnosis. Pituicytomas should be considered in the differential of a sellar/suprasellar lesion with glial and meningioma‐like cytological features.

Pituicytoma with pleomorphism: A case report with cytological findings

“…On cytology of previously reported cases, 5–7 pituicytoma cells generally form cohesive fascicles, some of which may adhere to blood vessels. Storiform and palisading patterns can be seen.…”

“…Metastatic tumors are also included. Since radiologic images of pituicytoma and these tumors may resemble each other, especially pituitary adenoma, 5,6 it is difficult to diagnose pituicytoma only by radiological findings. In contrast, cytological differentiation of pituicytoma from above tumors seems rather easy.…”

“…Tumor cells are noncohesive or appear as flat clusters. 6 Craniopharyngioma shows sheets of cohesive epithelial cells with peripheral palisading resembling basal cells. 8 Germinoma shows the two-cell pattern: large, round to oval tumor cells mix with small lymphocytes.…”

“…In general, pituicytoma lacks cellular atypia, so that pilocytic astrocytoma and meningioma are mentioned for differential diagnosis. 4,6,7 High-grade glioma commonly shows high cell density on crush cytology. Small tumor cells with fine cytoplasmic processes are usually predominant, accompanying astrocyte-like cells with eosinophilic cytoplasm.…”

“…Rosenthal fibers and eosinophilic granular bodies are occasionally observed. [6][7][8] Meningioma can occur around the sellar turcica, and a case extended into the sellar turcica has been reported. 8,10 On cytology, there are cohesive clusters exhibiting whorl structures.…”