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Case Reports

Abstract

INTRODUCTION

Waldenstrom’s macroglobulinaemia (WM) is a low-grade lymphoproliferative disorder characterized by bone marrow infiltration with small B lymphocytes, lymphoplasmacytoid cells and plasma cells associated with circulating monoclonal IgM paraprotein.

CASE DESCRIPTION

We describe the case of a 74-year-old female who developed confluent erythematous plaques on the right loin that spread anteriorly to the abdomen and chest over a period of 4 months. She was previously diagnosed with WM, which had MYD88 L265 mutation.

Punch biopsy from the back showed a superficial band-like and mid dermal perivascular nodular infiltrate of atypical small to medium lymphoid cells and occasional plasma cells. The atypical cells were +CD20, -CD3, +bcl-2, +CD10, -bcl-6, -MUM1, -CD5, -CD23 and -CD138. Immunohistochemistry and direct immunofluorescence showed IgM positivity and kappa light chain restriction. IgG and IgA were negative. Ki-67 showed a proliferative index of 20%. Further immunohistochemistry performed on previous bone marrow biopsy showed a similar immunohistochemical profile. This is in keeping with cutaneous involvement by CD10 positive WM.

DISCUSSION

Specific cutaneous manifestations of WM are uncommon. CD10 is usually expressed in follicular lymphoma. However, one study demonstrated CD10 expression in 7% of cases. Furthermore, the study also demonstrated the expression of CD5 and CD23 in 9% and 35% of cases, and co-expression of CD23 with CD10 and CD5 in 27% and 67% of cases respectively, mimicking other low grade B cell lymphoproliferative disorders.

CONCLUSION

The rare occurrence of cutaneous involvement by CD10 positive WD could pose a potential diagnostic pitfall. This could be mitigated by clinicopathological correlation.