Microcystic pseudoglandular plexiform cutaneous neurofibroma.

Glandular structures are well documented to appear in peripheral nerve sheath tumors. These epithelial elements are usually present in malignant peripheral nerve sheath tumors although a few cases of glandular benign peripheral nerve sheath tumors have also been described, most of them being schwannomas. A neurofibroma with glands is considered to be a rare type of divergent differentiation, but a neurofibroma containing gland-like or pseudoglandular structures have not, to our knowledge, been described. We report a 33-year-old patient with a well-demarcated dermal neoplasm, composed of neoplastic Schwann cells, perineurial-like cells and fibroblasts in a matrix with collagen fibers and myxoid areas. A part of the tumor consisted of microcystic gland-like spaces lined by flat cells. These cells were either S100 positive or negative, with no epithelial membrane antigen, cytokeratin or CD31 immunostaining. Recognition of the presence of pseudoglandular elements in neurofibromas is important to distinguish them from other tumoral lesions, some of them with malignant potential.