Non-Hodgkin's lymphomas presenting as cutaneous lesions

To analyze the spectrum of Non-Hodgkin's Lymphomas (NHL) presenting as skin lesions and to see the histological type, age, sex incidence and site predilection of different types of NHLs and to correlate our findings with western published data.

A retrospective descriptive case series study.

All NHLs (nodal and extra nodal) diagnosed between January 1991-December 2001 in the section of Histopathology, Department of Pathology, The Aga Khan University, Karachi were retrieved by using SNOMED coding system. Cases were reviewed and those presenting with skin involvement were selected. Further characterization of these tumours was done by morphology and Immunohistochemistry. Panel of antibodies included leukocyte common antigen (CD45), Pan B markers (CD20 and CD 79a), Pan T markers(UCHL1), Ki-1(CD30) and epithelial membrane antigen (EMA).

The total number of NHLs (nodal and extra nodal) diagnosed in our department during the study period of 10 years were 1610. Out of these, 133 cases (8.26%) of NHLs presented with skin involvement. Out of these 44.4% (n=59) were NHLs of B cell phenotype while 23.3% (n=31) cases were of T cell phenotype. Out of 133 cases, 14(10.5%) were of mycosis fungoides (MF), and 3 (2%) each were of anaplastic large cell lymphoma (ALCL:Ki-1), lymphoma and lymphoblastic lymphoma/leukemia. In 17.3% (n=23) cases the phenotype could not be ascertained. There were 97(73%) males and 36(27%) females with a M:F ratio of 2.7:1. All types of NHLs showed a site predilection for the head and neck region except MF which presented mainly as generalized body lesions.

NHLs presenting as skin lesions are more commonly of B cell phenotype followed by T cell phenotype (NOS) and mycosis fungoides. Probable reasons for the high frequency of cutaneous involvement by B-cell NHL are the advanced nature of the disease at the time of presentation and biological behavior of the tumors in our population.