The first description of a primary cutaneous diffuse large B cell lymphoma was by Willemze et al in 1987 who described a group of elderly women with cutaneous large cell lymphomas with tumours in the legs and a worse prognosis ( Am J Pathol. Feb 1987; 126(2): 325–333).
Primary cutaneous diffuse large B cell lymphoma, leg type is a type of high grade cutaneous B cell lymphomas that was included as a separate entity in the WHO 2008 lymphoma classification. It forms about 20% of all cutaneous B cell lymphomas and about 4% of all cutaneous lymphomas. It is more common in women and the median age of occurrence is the 7th decade.
Primary cutaneous large B cell lymphoma is characterized by a monotonous, diffuse, non-epidermotrophic infiltrate that is CD 20 and CD79a positive. and almost always express BCL2, IRF4/MUM1 and FOX-P1. The latter three markers are not expressed in in the primary cutaneous follicular centre cell lymphoma another type of primary cutaneous B cell lymphoma. BCL6 is usually expressed but CD10 is not.
DLBCL-LT is a disease of elderly women (M:F:12-4, median age 70 years). Though called leg type, only 85-90% of the primary cutaneous DLBCL, leg type occur in the legs. The remaining occur at other sites. Patients present with a rapidly growing red or reddish blue nodule on one or both the legs. Patients may have ulceration and may be confused with venous ulcer. Unlike other cutaneous lymphomas primary cutaneous DLBCL, leg type disseminates to non-cutaneous sites.
As DLBCL-LT has a tendency to disseminate to extra-cutaneous sites than other cutaneous lymphomas radiation is less effective in this disease. . A complete response rate of 88% with a high (58%) relapse rate has been reported. relapses are in the in field and extra-cutaneous.
R-CHOP is the standard first line therapy. Dose reduction may be needed in elderly. Single agent rituximab is also an option but is associated with a high rate of recurrences. Linelidomide has been used in patients with relapse.