Abstract

Glandular schwannoma represents a rare neurocristic tumor characterized by the presence of glands within a nerve sheath tumor. Historically, the phenomenon was first recognized in malignant peripheral nerve sheath tumors (MPNST) that contained benign glands. Tumors containing atypical glands within MPNST were also reported. Using ultrastructural methods, Woodruff demonstrated that the glands exhibit enteric differentiation. More recently, rare cases of benign glandular schwannoma have also been reported. We present the case of a primary cutaneous adenocarcinoma arising from a benign nerve sheath tumor, namely glandular schwannoma. A 53-year-old female presented with a 20-year history of a thigh mass that had recently enlarged. Excision revealed a circumscribed spindle cell tumor distributed in a haphazard, vaguely fascicular arrangement. Within the tumor, entrapped glands ranged from benign to highly atypical with abundant luminal and extraglandular mucin. Goblet cells were scattered throughout both benign and atypical glands. By immunohistochemistry, the spindle cell component showed varying degrees of SOX10 positivity. The benign and atypical glands expressed CK20 and CDX2. Because of the enteric phenotype of the glands, metastatic adenocarcinoma with spread to a nerve sheath tumor was suspected, but extensive clinical and radiographic evaluation was negative for primary adenocarcinoma elsewhere. This case demonstrates that primary adenocarcinoma can arise within a benign nerve sheath tumor, namely glandular schwannoma. While adenocarcinoma could metastasize to a cutaneous schwannoma, we interpreted the presence of both benign and atypical glands in the same tissue as excluding that possibility. An enteric immunophenotype should be expected in the context of glandular schwannoma.