Small-Vessel Vasculitis or Perifolliculitis in Small-Fiber Neuropathy With TS-HDS, FGFR-3, or Plexin D1 Antibodies.

Introduction: Small-fiber neuropathy (SFN) is highly prevalent but often idiopathic. TS-HDS, FGFR-3, and Plexin D1 autoantibodies (seropositive) may be present in more than 40% of idiopathic cases. Another autoimmune biomarker is a non-length-dependent (NLD) skin biopsy pattern.

Cutaneous Rosai-Dorfman disease with increased number of eosinophils: coincidence or histologic variant?

Rosai-Dorfman disease (RDD) is characterized histologically by a dense histiocytic infiltrate with emperipolesis and associated lymphocytes, plasma cells, and neutrophils. Eosinophils are not commonly associated. We report a patient with initial thymus and pituitary gland involvement by RDD, who later developed papules on the groin and axilla.

Cutaneous adnexal tumor with an unusual presentation--discussion of a potential diagnostic pitfall.

The clinical presentation of skin adnexal tumors is nonspecific, and histologically; the differential diagnosis between primary cutaneous adnexal malignant carcinomas and metastatic tumors with a visceral origin can be challenging. We report a patient with history of invasive ductal carcinoma of the breast who presented with a 1-cm erythematous palpable lesion on her right calf. The biopsy showed an intradermal proliferation of malignant epithelioid cells with ductal differentiation, histologically compatible with metastatic breast carcinoma.

Unusual presentation of multiple epithelioid cell histiocytomas.

Epithelioid cell histiocytoma (ECH) is a variant of dermatofibroma that presents typically as a solitary nodule. We report a case of a 20-year-old male who presented with a bleeding nodular lesion on the left arm followed a month later by a nodule on the right nostril. Both lesions had epithelioid cells in the dermis, with focal Factor 13a and CD68 immunoreactivity.