ALK-Negative Systemic Anaplastic Large Cell Lymphoma With Multifocal Cutaneous Involvement Responding to Brentuximab Vedotin.

Systemic anaplastic large cell lymphoma with cutaneous involvement can mimic other malignancies and delay treatment. A 71-year-old Filipino woman had 18 months of minimally symptomatic plaques and nodules; a right-hip nodule enlarged to an 8 × 8 × 5-cm mass. She underwent radical wide excision of the right-hip mass and scalp nodules; only the hip specimen was submitted for histopathology and was read as a malignant spindle cell tumor favoring alveolar rhabdomyosarcoma, with rapid recurrence at the hip and scalp surgical sites. On referral, she had plaques and nodules, crusted scalp lesions, and lymphadenopathies. Repeat biopsies from scalp and recurrent hip lesions showed a dermal-subcutaneous infiltrate of large atypical lymphocytes with mitoses and periadnexal/intravascular involvement; immunohistochemistry was CD30/CD3/CD45 positive and ALK/EMA negative, consistent with ALK-negative systemic ALCL with cutaneous involvement. Staging revealed stage IV disease with extranodal metastases and elevated LDH. After a dose of ifosfamide/etoposide elsewhere, therapy was revised to ifosfamide, carboplatin, and etoposide plus brentuximab vedotin, with marked improvement by 2 cycles and cutaneous resolution by 5; she died of cardiopulmonary failure before the sixth cycle. This case underscores generous sampling, focused immunohistochemistry, and staging; negative ALK/EMA does not exclude systemic disease, and CD30-directed therapy can yield rapid cutaneous responses.