Palmar Fasciitis and Polyarthritis With Erosive Disease: A Case Report

Palmar fasciitis and polyarthritis is a rare paraneoplastic syndrome that is nonerosive and associated with a high mortality rate. Metastatic undifferentiated epithelial carcinoma of unknown primary was diagnosed in a 59‐year‐old man who simultaneously developed palmar fasciitis and polyarthritis. Bone radiographs showed erosive disease of the hands and feet and bony periostitis. Biopsy of an erosion showed dense fibrous tissue eroding articular cartilage. Immunofluorescence analysis of the palmar fascia showed diffuse IgG deposition. After radical neck dissection and prednisone therapy, the clinical findings stabilized and did not progress during the 28 years of follow‐up. This case provides new information to the literature, including erosive disease with histopathologic findings, a rare tumor type, and immunoglobulin response in the palmar fascia and long survival.