Unusual histopathological features of cutaneous leishmaniasis identified by polymerase chain reaction specific for Leishmania on paraffin‐embedded skin biopsies

Summary Background  Cutaneous leishmaniasis (CL) is rare in Northern Europe and may be overlooked because colleagues have little experience with it. Objectives  To identify manifestations of CL that may escape diagnosis. Methods  Correlation of clinical diagnosis and histopathological findings in 28 biopsy specimens taken from 19 patients with CL confirmed by polymerase chain reaction (PCR) specific for Leishmania . Results  In only one patient was the clinical diagnosis CL; other diagnoses included: malignant epithelial neoplasms (5), follicular cyst (2), atypical mycobacteriosis (1), sarcoidosis (2) and lymphoma (1). Lesions were single (15) or few (4) nodules predominantly situated on the extremities or face (16). Histopathological findings were diagnostic of CL in only 10 cases. In nine cases Leishmania was not identified microscopically; histopathological diagnoses were: granulomatous dermatitis (6), lupoid rosacea (1), foreign body granuloma (1) and granuloma annulare (1). Unaltered epidermis (9), nodular infiltrates (5), numerous multinucleated histiocytes (3), palisaded granulomas with fibrinoid centres (2), sarcoidal granulomas (4) and elastophagocytosis (1) misled the histopathologists in these cases. Conclusions  CL seems often to be misdiagnosed clinically in countries where it is not endemic. Histopathologically, CL may be misinterpreted as sarcoidosis, foreign body granuloma, lupoid rosacea and granuloma annulare, especially when Leishmania is not seen microscopically. We suggest that in Northern Europe, PCR for Leishmania ‐specific DNA should be performed routinely in any granulomatous dermatitis presenting as a single or few nodules on the extremities or face, even when a diagnosis of CL was not considered by the referring clinician.