Extraneural Sclerosing Perineurioma of the Tongue

Perineurioma (PN) is an uncommon benign peripheral nerve sheath tumor. For the rarity of this tumor in the oral cavity, otolaryngologists and oral surgeons might not be familiar with this entity. Perineuriomas are typically benign and complete excision is deemed adequate management. Thus, their histological recognition is mandatory to avoid unnecessary overtreatment. We report the clinicopathologic findings of an uncommon variant, the Extraneural Sclerosing PN, in an unusual and never described site, the tongue.

A Sclerosing Perineurioma With Collagen Rosette Formation: Benign Mimic of Low-Grade Fibromyxoid Sarcoma

We report the case of a sclerosing perineurioma with conspicious collagen rosette formation in a 20-year-old male presenting with a firm, painless nodule on the palmar side of his right ring finger. The main differential diagnosis is a low-grade fibromyxoid sarcoma. The distinction between these entities is important because low-grade fibromyxoid sarcoma has a metastatic potential, while, as a rule, perineuriomas are benign. The presence of collagen rosettes in this current case makes this distinction even more difficult given that approximately 30% of low-grade fibromyxoid sarcoma cases show the focal presence of collagen rosettes. The demonstration of the characteristic t(7;16), t(11;16) or t(11;22) translocations (resulting in the FUS-CREB3L2, FUS-CREB3L1 or EWSR1-CREB3L1 fusion genes, respectively) or immunoreactivity for MUC4, a recently described sensitive and specific marker for low-grade fibromyxoid sarcoma, remain the gold standard in the diagnosis of low-grade fibromyxoid sarcoma, differentiating it from perineurioma. This case is, to our knowledge, the first report on collagen rosettes in sclerosing perineurioma, extremely well mimicking low-grade fibromyxoid sarcoma, and further expanding the morphological spectrum of this rare subtype of perineurioma.