Double crush syndrome of the median nerve revealing a primary non-Hodgkin's lymphoma of the flexor digitorum superficialis muscle.

Extranodal manifestations of lymphoma are well described in the literature and occur in 20 to 30% of patients. Skeletal muscle involvement is rare. We describe the case of a patient with non-Hodgkin's lymphoma in a forearm muscle. At the age of 86, the featured patient started experiencing continuous, progressive and high intensity pain that was more frequent at night and localized in the right dominant hand. It was associated with paresthesia and hypoesthesia, primarily in the thumb, index finger and middle finger. Clinical examination and electrodiagnosis led to the diagnosis of carpal tunnel syndrome. The patient underwent carpal tunnel release at a private hand center. The progression was unfavorable. Additional clinical examination and electrodiagnosis showed compression of the anterior interosseous nerve (double crush syndrome). The patient was referred to our university hand center for further management. Magnetic resonance imaging showed a large mass of about 20 cm occupying the entire anterior compartment of the forearm and enclosing the median nerve. Biopsies were performed and revealed a diffuse large B-cell primary non-Hodgkin's lymphoma. The patient underwent chemotherapy and radiotherapy. Six months later, the patient was in complete remission. Muscular involvement during lymphoma is rare. Biopsy is mandatory; needless radical surgery can be avoided because lymphoma is primarily a non-surgical disease. The key points of the treatment process are reviewed. [ABSTRACT FROM AUTHOR]