14 | cutaneous leishmaniasis mimicking b-cell pseudolymphoma: A diagnostic challenge in an endemic mediterranean area

Cutaneous leishmaniasis is a zoonotic disease endemic in several areas of the Mediterranean basin, including Liguria, characterized by heterogeneous clinical and histological features that can complicate diagnosis. We report the case of a male patient with a history of frequent exposure to woodland areas, presenting with a painless small nodule located on the right auricular helix, without sytemic symptoms. A skin biopsy revealed a mixed lymphocytic infiltrate, with a predominance of B lymphocytes and granulomatous features, initially diagnosed as a B-cell pseudolymphoma. Topical corticosteroid therapy was therefore initiated, with no clinical improvement. Three months later, due to persistence of the lesion, a second biopsy was performed, showing a prevalent granulomatous dermatitis with an infiltrate of lymphocytes, plasma cells, and macrophages. Major granulomatous skin diseases, and also Borrelia-associated B-cell pseudolymphoma, were excluded through laboratory tests and serological investigations. Giemsa staining and microscopic examination for amastigotes were negative, and confirmatory PCR testing could not be performed. Serological testing for anti-Leishmania antibodies resulted in mildly elevated titers. The diagnosis was therefore established on a clinical-serological basis and confirmed ex adiuvantibus by the response to Amphotericin B therapy, which led to complete resolution of the lesion. This case highlights the importance of considering cutaneous leishmaniasis in chronic skin lesions involving exposed body areas, and underscores the need to critically integrate clinical, histopathological, and epidemiological data in the diagnostic workup.