Lack of BRAF-V600E Mutation in Papillary Tumor of the Pineal Region

Abstract

Abstract BACKGROUND: Papillary tumor of the pineal region (PTPR) is a rare central nervous system tumor with a variably aggressive clinical behavior, corresponding to World Health Organization grade II/III. Very little is known about the genetic mutations comprising PTPR. Recent studies have shown that other papillary tumors harbor BRAF-V600E mutations, namely papillary thyroid carcinoma and papillary craniopharyngioma, the latter of which is a midline central nervous system papillary tumor like PTPR. OBJECTIVE: To determine whether PTPR may contain the BRAF-V600E mutation. METHODS: A search of our institutional files was conducted for PTPR cases. Chart review was performed to obtain demographics and pertinent clinical information when possible. Immunohistochemistry was performed with an anti–BRAF-V600E antibody for cases with additional material for testing. RESULTS: We identified 19 PTPR cases occurring in 16 patients. The patient age range was 1 to 73 years (average, 32.2 years). The male-to-female ratio was 1:1. Thirteen patients presented with symptoms of obstructive hydrocephalus, and the other 3 had unknown presenting symptoms. Initial magnetic resonance imaging characteristics tended to include partially cystic masses with heterogeneous postcontrast enhancement. The tumor size ranged from 1.1 to 4.4 cm (average, 2.5 cm). CONCLUSION: Of the 16 patients, 13 had additional material for BRAF-V600E immunohistochemistry, all of which demonstrated negativity for BRAF-V600E. This rate is unlike that of other midline papillary tumors and suggests that these tumors, despite their papillary phenotype, may have a distinctive molecular background.