Extraneural perineurioma of the face: an unusual cutaneous presentation of an uncommon tumour

Intraneural perineurioma: a systematic review with illustrative cases

CONTEXT

Intraneural perineurioma may be confused with other "onion bulb" Schwann cell entities (localized hypertrophic neuropathy, reactive/demyelinating processes, or inherited polyneuropathies of Charcot-Marie-Tooth/Dejerine Sottas) due to similar clinical, radiologic, and histologic features. Perineurial and Schwann cells can only be differentiated by ultrastructure and immunohistochemsitry.

OBJECTIVE

To identify and summarize the clinicopathologic features of true cases of intraneural perineurioma from the English language literature.

DATA SOURCES

A systematic review was performed on definitive intraneural perineuriomas identified through Medline. Baylor College of Medicine-affiliated hospitals' anatomic pathology databases yielded 2 illustrative intraneural perineurioma cases.

STUDY SELECTION

Intraneural perineurioma inclusion criteria consisted of characteristic histology and confirmation of perineurial cell lineage by either immunohistochemistry (epithelial membrane antigen positive, S100 protein negative) and/or ultrastructural analysis (thin cytoplasmic processes with an incomplete basal lamina, poorly formed tight junctions, and pinocytotic vesicles).

DATA EXTRACTION

Clinicopathologic data were extracted from all identified articles, with subsequent statistical analysis of the following parameters: age, sex, race, tumor location, tumor size, duration of symptoms prior to diagnosis, treatment modalities and outcomes measures, follow-up assessment for tumor recurrence and metastasis, clinical features (history of trauma, motor/sensory abnormalities, clinical/family history), and diagnostic workup (routine histology, immunohistochemistry, ultrastructural analysis, and molecular/cytogenetic characteristics).

CONCLUSIONS

Intraneural perineurioma is a neoplastic proliferation of perineurial cells with unique immunohistochemistry and ultrastructural features, and it is distinct from other onion bulb Schwann cell-derived entities. Despite harboring molecular abnormalities of the long arm of chromosome 22, intraneural perineurioma has not been associated with neurofibromatosis. Intraneural perineurioma is a benign peripheral nerve sheath tumor that does not recur or metastasize.

[Cutaneous perineurioma. Clinical and histological findings and differential diagnosis]

Perineuriomas, composed almost exclusively of EMA (epithelial membrane antigen) positive cells, represent a rare and distinct entity in the spectrum of nerve sheath tumours. At present three subtypes, including intraneural and extraneural perineurioma as well as sclerosing perineurioma, can be distinguished; atypical and malignant perineuriomas are extremely uncommon. We analysed the clinicopathological and immunohistochemcial features of 13 cases of cutaneous perineurioma. The neoplasms arose in adult patients (age range from 18 to 71 years) and were seen on the hand (six cases), the thigh (three cases), the lower leg (two cases), the forearm (one case) and in perinasal location (one case). Morphologically, seven neoplasms showed features of dermatofibroma-like perineurioma, four lesions were consistent with sclerosing perineurioma, one cellular lesion resembled a solitary fibrous tumour, and one case was diagnosed as atypical/malignant cutaneous perineurioma; no local recurrences or tumour progression has been reported so far. The differential diagnosis of various variants of cutaneous perineurioma from other mesenchymal lesions as well as melanocytic and epithelial neoplasms is discussed.

Intraoral perineurioma: report of a case with a review of the literature

Perineurioma is a rare benign peripheral nerve sheath tumour that occurs as an intraneural or extraneural form. To the best of our knowledge, this is the second reported case of an intraoral submucosal extraneural perineurioma. The tumour was symptomless, measured 2 cm in diameter and occurred in the nasolabial fold of a 46-year-old black female. Awareness of the occurrence of this neoplasm in the oral cavity is important to promote detection and differentiation from other benign spindle tumours, which occur intraorally. All reported cases of perineurioma have been benign and cure is effected by localized surgical excision.

Intra-osseous soft tissue perineurioma of the inferior alveolar nerve

This report describes an intra-osseous perineurioma affecting the inferior alveolar nerve, the second at this site, of a 53-year-old man. It produced a well defined, partially corticated, round radiolucency associated with resorption of the root apices of 36 and 37. Histology showed a circumscribed, partially encapsulated cellular tumour composed of bland spindle cells with undulating nuclei and indistinct cell membranes arranged in interlacing fascicles. The tumour was strongly positive for epithelial membrane antigen, collagen IV and laminin, with only scattered S100-positive cells and lack of CD34 expression. Electron microscopy showed elongated cells with continuous external laminae of basement membrane-like material, subplasmalemmal densities, desmosome-like junctions, and variable numbers of micropinocytotic vesicles. The lesion was surgically excised and in 9 months there has been no recurrence.