Background: Primary cutaneous CD30+ anaplastic large-cell lymphoma is a rare form of non-Hodgkin's lymphoma, which is restricted to the skin.
Case description: A 50-year-old man presented with an asymptomatic tumorous area in the groin that had appeared within the previous week, and a longer history of a transient red, flaking area in the popliteal space. Histopathological findings were consistent with CD30+ anaplastic large-cell lymphoma. Staging demonstrated no extracutanous spread. The skin lesions disappeared without treatment within 3 months.
Conclusion: Primary cutaneous CD30+ anaplastic large-cell lymphoma is a rare condition. It has a histopathological picture of a diffuse proliferation of large atypical anaplastic cells, suggesting an unfavourable disease course. However, this condition is characterised by a indolent course and favourable prognosis since spontaneous complete regression can occur.