P04 Leg ulceration in a patient with antisynthetase syndrome

Abstract

Abstract A 42-year-old woman presented with leg ulceration on a background of antisynthetase syndrome and immunosuppression with rituximab, azathioprine and prednisolone. The initial lesion was an erythematous patch on the lower leg, which increased in size with violaceous changes. The area subsequently broke down to form an ulcer. On examination, she had a 7-cm ulcerating lesion with central necrosis. Clinically, the appearance was suspicious of pyoderma gangrenosum; biopsy demonstrated scarring without features of vasculitis, atypia or malignancy. The ulcer did not show improvement as expected after oral and topical steroid treatment, with new fleshy nodular growth. Repeat biopsy showed angiocentric atypical lymphocytes with positive Epstein–Barr virus (EBV)-encoded RNA (EBER) staining. Further incisional biopsy demonstrated large, atypical B lymphocytes with a diffuse sheet-like morphology and a poorly circumscribed base. Immunohistochemistry was positive for CD79a, CD30, CD20, MUM1, BCL6, and EBER. Overall, the findings were consistent with EBV-positive diffuse large B-cell lymphoma (DLBCL). The main differential diagnosis was EBV-positive mucocutaneous ulcer (MCU), another EBV-associated lymphoproliferative disorder, albeit with an indolent course (Dojcinov SD, Venkataraman G, Raffeld M et al. EBV positive mucocutaneous ulcer—a study of 26 cases associated with various sources of immunosuppression. Am J Surg Pathol 2010; 34:405–17). In this case, the diffuse sheet-like morphology and poorly circumscribed base favoured EBV-positive DLBCL. The lesion fully healed with withdrawal of immunosuppression and treatment with rituximab therapy, and involved field radiotherapy. First described in 2003, EBV-positive DLBCL is a rare, classically aggressive lymphoma initially believed to only occur in patients older than 50 years of age (Oyama T, Ichimura K, Suzuki R et al. Senile EBV+ B-cell lymphoproliferative disorders. Am J Surg Pathol 2003; 27:16–26). Since the revision of the World Health Organization classification in 2016, it is also recognized to present in younger patients, with an associated better prognosis. EBV-positive DLBCL occurs in both nodal and extranodal sites. Therefore, cutaneous presentations must complete staging investigations to rule out skin involvement secondary to a nodal lymphoma. Our patient highlights a rare complication of immunosuppression. We illustrate the relevance of considering rare causes of ulceration in patients with autoimmune conditions and immunosuppression and demonstrate the importance of considering malignancy in a nonhealing ulcer. Multiple biopsies may be needed in ulcers that poorly respond to treatment. While EBV-positive DLBCL and EBV-positive MCU can be difficult to differentiate, it is vital for prognostication.