Tenosynovitis with rice body formation presenting as a cutaneous abscess.

A 62-year-old woman with a past medical history of rheumatoid arthritis was referred to the Department of Dermatology because of an enlarging cutaneous lesion on the right thumb which resembled a soft tissue infection. She had received antibiotics without significant improvement. Clinical examination revealed an erythematous nodule involving almost the whole surface of the distal phalanx with spontaneous drainage of countless of small yellowish ovoid granules. Histopathologic study of these structures showed an inner core of amorphous acidophilic material with some interspersed chronic inflammatory cells and a surrounding thin fibrin layer. Special stains and cultures were negative for parasites, bacterium and mycobacterium. Magnetic resonance imaging (MRI) revealed distension of the first and fifth finger flexor sheaths and common finger flexor sheath. These areas were filled by fluid and multiple small nodular lesions. A diagnosis of non-infectious rice body tenosynovitis was rendered and surgical removal was performed. Total recovery was observed with no evidence of recurrence after 6 months of follow-up. To our knowledge, this is the first report of rice body tenosynovitis presenting as a pseudoinflammatory cutaneous lesion with evolution to a cutaneous fistula with drainage of rice grain-like structures. The description of this impressive and peculiar clinical and histopathologic picture is important to further recognize similar cases.