Cytologic features of papillary tumor of the pineal region: A case report showing tigroid background

Abstract

Papillary tumor of the pineal region (PTPR) is a rare neuroepithelial tumor of the pineal region of adults. We herein describe on a 34-year-old female the cytologic features of a PTPR studied using Diff-Quik stain. The patient presented hydrocephalia secondary to a pineal tumor. During surgery an intraoperative pathologic consultation was requested. Smears were hypercellular with numerous papillary tissue fragments and single cells. Papillary fragments had an evident inner vascular core. Neoplastic cells displayed moderate pleomorphism, plasmocytoid morphology, and cytoplasmic fragility. The background had a foamy, lace-like, tigroid appearance. Pathologic analysis revealed morphologic and immunohistochemical features of PTPR. When evaluating smears of a pineal tumor in an adult, the presence of true papillary structures and numerous single cells should raise the possibility of PTPR. This is particularly useful during intraoperative pathologic evaluation since, on frozen sections, the epithelial morphology of the tumor may be misleading. The papillary morphology which gives name to this neoplams is best appreciated on squash smears. An interesting feature seen in the present case was a prominent tigroid background. This is a characteristic cytologic feature observed in Romanowsky-type stained smears of germinoma and related tumors. It can be seen in other clear cell, glycogen-rich tumors. PTPR shares with these neoplasms its clear cell morphology and PAS positive cytoplasmic granules. As seen from the present case, germinoma is not the only tumor of the pineal region that may show a tigroid background. Cytologic features of PTPR differ from those of germinoma allowing their distinction during intraoperative consultations. Diagn. Cytopathol. 2016;44:1098-1101. © 2016 Wiley Periodicals, Inc.

Cytologic Features of Ventricular Tumors of the Central Nervous System: A Review with Emphasis on Diff-Quik Stained Smears

“…1e). Cytoplasmic fragility and naked nuclei are frequent, and as mentioned before, this tumor may show a proteinaceous, tigroid background [25]. This is likely related to the clear cell morphology and glycogen content that are characteristic of the tumor.…”

“…It is considered to derive from specialized ependymal cells of the vestigial subcommisural organ remnant, which may explain the morphologic similarities with ependymoma. The few cytologic descriptions available reveal a hypercellular lesion with numerous papillary tissue fragments and single neoplastic cells [25][26][27]. Indeed, the papillary morphology of the tumor is better appreciated in cytology than in histologic sections.…”

“…A tigroid background is not exclusive to germinomas and can be seen in other glycogen-rich tumors that typically show clear cell morphology. In the context of ventricular tumors, papillary tumors of the pineal gland can also exhibit a relevant tigroid background [25]. In addition to germinomas, teratomas, yolk sac tumors, embryonal carcinomas, choriocarcinomas, and mixed forms are also possible.…”

A comprehensive review of the “tigroid” background cytological concept: what, when, where and why?

“…We reported its presence in a papillary tumour of the pineal region a rare and peculiar neoplasm that has a high glycogen content ( Fig. 3D ) 24 . Both germinoma and papillary tumour share a common pineal location and a TB.…”

Papillary tumor of the pineal region accompanied by Parinaud’s syndrome: magnetic resonance imaging findings

“…Its origin is uncertain, the most widely accepted hypothesis is that it originates from ependymal cells of the subcommissural organ ( 4 , 5 ) . Histologically, PTPR is characterized by the presence of epithelial and papillary aspect structures with high cellularity and moderate-to-high mitotic activity ( 4 - 6 ) . It can cause headache, due to obstructive hydrocephalus, and Parinaud’s syndrome ( 7 ) , due to compression of the dorsal midbrain, specifically the periaqueductal region ( 8 ) .…”