LAUSR

which showed features of MALT lymphoma without granulomatous reaction (Fig. 2c–j). Monoclonal B-cell proliferation was confirmed by immunoglobulin heavy-chain gene rearrangement analysis of the lymph node. The pattern of monoclonal B-cell proliferation was the same in the skin and lymph node lesions. Granulomatous reactions due to infectious aetiologies were excluded. We diagnosed the skin lesions as cutaneous infiltrates of MALT lymphoma. Neither Sj€ ogren syndrome nor Hashimoto thyroiditis was detected. R-CHOP therapy (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone) was administered because of the constant itching caused by skin lesions, resulting in partial response. It is important but sometimes difficult to diagnose cutaneous lymphoma with granulomatous reaction correctly, because of the histopathological similarity with other granulomatous skin diseases. In our patient, a granulomatous reaction was observed in the skin but not in the cervical lymph node, although both were involved in the MALT lymphoma. This finding agrees with previous reports showing that the skin is the common site of granulomatous infiltrates associated with lymphoma. Some reports suggested that patients with a granulomatous reaction have a better prognosis than those without. The skin lesion with granulomatous reaction in our patient showed less MALT lymphoma cells than the lymph node without granulomatous reaction. We speculate that cutaneous granulomatous reaction may represent a patient’s immunological antilymphoma response that is likely to occur specifically in the skin. In summary, our case report emphasises that IHC and immunoglobulin heavy-chain gene rearrangement analyses can be a useful part of the diagnostic workup for patients with a history of MALT lymphoma who present with cutaneous granulomatous lesions, even if findings suggestive of lymphoma involvement are absent in the HE-stained specimen.