Multiple skin nodules as a sign of relapsed systemic anaplastic large cell lymphoma in an adolescent

Anaplastic large cell lymphoma (ALCL) is a rare T-cell non-Hodgkin lymphoma, accounting for 2–3% of all non-Hodgkin lymphomas. While primary cutaneous ALCL is well documented, secondary cutaneous involvement from systemic ALCL is an uncommon presentation and can signify disease progression or relapse. Early recognition is key to timely management.
A 15-year-old patient with a history of systemic ALCL presented with multiple, rapidly enlarging, firm nodules and plaques over the face, trunk, and extremities. Lesions were tender and non-ulcerated, and this was her second episode within the past year, after which she defaulted on treatment. She also complained of exertional dyspnoea. Skin biopsy revealed acanthosis of the epidermis and a heavy, nodular dermal infiltrate composed of atypical lymphoid cells, including large pleomorphic cells, with small reactive lymphoid cells observed in the background. Immunohistochemistry for CD30 showed strong diffuse membrane positivity in large cells, confirming cutaneous metastasis of systemic ALCL. CD3 and CD20 were negative, and ALK-1 testing was not performed due to unavailability.
Cutaneous metastasis in systemic ALCL is rare, especially among paediatric and adolescent populations. It can mimic infections, drug reactions, or other malignancies, thereby complicating diagnosis. Recognising skin involvement is significant, as it can indicate relapse. Histopathology with immunophenotyping is essential for establishing a definitive diagnosis. Early detection facilitates timely systemic therapy and clinical management. This case highlights the importance of vigilance for new skin lesions in patients with a history of systemic ALCL, emphasising the crucial role of dermatological assessment in ongoing follow-up care.