A girl aged 5 years with no history of interest presented with an erythematous lesion measuring 1.5 cm in the scapular region with raised margins and fine desquamation that had appeared a month earlier (Fig. 1). The initial treatment was oral antibiotherapy based on a working diagnosis of bacterial cutaneous infection (impetigo/ecthyma), without improvement. The lesion persisted and progressed to necrotic ulceration associated with local lymphadenopathy (Fig. 2), prompting performance of a skin biopsy. The laboratory workup was unremarkable, without elevation of acute phase reactants or any other relevant findings.
The histological analysis led to diagnosis of ALK-positive anaplastic large cell lymphoma (ALK+ ALCL), with diffuse CD30 expression, ALK expression, and an aberrant T phenotype (CD3−). Staging tests (bone marrow biopsy and aspiration, cerebrospinal fluid) were negative. The PET/CT scan revealed axillary and supraclavicular lymphadenopathy (stage ii) (Fig. 3). The pattern was classified as “high risk” (ALCL-99) on account of the cutaneous and mediastinal involvement, and the patient started chemotherapy, with favorable outcomes.1
ALK-positive ALCL is a type of non-Hodgkin lymphoma that is rare in childhood and may manifest as an isolated cutaneous lesion, mimicking common infections.2,3 A biopsy should be promptly performed when atypical cutaneous lesions persist and do not respond to antibiotherapy. This case highlights the need to consider a malignant etiology in the differential diagnosis of persistent cutaneous lesions refractory to antibiotherapy or with associated lymphadenopathy.
The authors have no conflicts of interest to declare.
