Primary cutaneous Ki-1(CD30) positive anaplastic large cell lymphoma (ALCL) is an unusual tumor in the pediatric population. However, the nodal-based form of the disease compared with other histologic subsets of childhood non-Hodgkin’s lymphomas (NHL) more frequently involves skin, soft tissue, and bone. The objective of this article is to determine the histologic and immunologic characteristics of childhood primary cutaneous Ki-1(CD30) positive ALCL and its prognosis. The clinical data, histologic features and immunohistochemical profiles of skin biopsy specimens from 3 children with cutaneous Ki-1(CD30) positive lymphoma were reviewed. A literature search was performed and disclosed information on 5 childhood cases. The 3 patients with primary cutaneous Ki-1(CD30) positive ALCL all presented similarly as rapidly growing masses initially and clinically believed to be infectious/reactive processes. The diagnosis was established on the basis of histopathologic examination and immunohistochemical studies. Histologic sections revealed an extensive infiltrate of tumor cells extending throughout the entire dermis into the subcutaneous fat with frank ulceration in 1 patient. No significant epidermotropism was noted. Tumor cells exhibited striking cellular pleomorphism and a high mitotic rate with numerous atypical mitoses. Inflammatory cells were present in all patients. The tumor cells stained positively for Ki-1 antigen (CD30), epithelial membrane antigen, and for T-cell markers (UCHL-1, CD3). One of 3 cases, however, failed to stain for leukocyte common antigen (LCA). No clinically apparent adenopathy was observed in any of the patients. In all instances the patients developed recurrent disease in the skin at sites separate from the primary location. None of the patients demonstrated any involvement of lymph nodes, bone marrow, or other organ systems. All patients were treated with chemotherapy with good response. Primary cutaneous Ki-1(CD30) positive lymphoma is rare in children and is characterized by recurrences. The prognosis seems to be favorable. (J Am Acad Dermatol 1999;40:857-61.)