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Malignant trichilemmoma (MT) is cutaneous adnexal neoplasm of external hair sheath origin, whose histologic feature is often confused with those of malignant proliferating trichilemmal tumor (MPTT) . In order to investigate the possibility that MT might differ from MPTT clinically and histologically, we studied 37 cases of MT and 30 MPTT. MT regarded as the malignant counterpart of trichilemmoma, manifests as solitary keratotic or ulcerated nodules. MT is often misdiagnosed as Bowen disease. Microscopically MT consists of multiple intradermal epithelial lobules in continuity with the epidermis. The tumor is composed of large glycogenrich clear cells with peripheral palisading that exhibit areas of trichilemmal keratinization. Ultrastructurally intracytoplasmic focal dyskeratosis was observed. Despite the frequent presence of histologically malignant features, it has a relatively benign clinical behaviour. MPTT showed clinically ulcerated, teleangiectatic or keratotic nodules. Histologically, MPTT had the presence of cystic configuration that extended from epidermis into reticular dermis. They were more prone to local recurrence and metastasis. We conclude that histologic, ultrastructural, and immunohistochemical studies should be performed to offer a more complete definition and classification of these neoplasms.

Natural killer cells are large granular lymphocytes, which do not express CD3 surface antigen, nor rearrange (α, β, γ or δ) T cell antigen receptor (TCR) genes. This report covers a case of cutaneous natural killer cell lymphoma, followed by the occurrence of acute leukemia.In March, 1991, a 43-year-old male complained of the skin tumor on his back. The histopathological examination showed diffuse large cell lymphoma. Grenz zone was not recognized. The tumor cell's surface phenotypes were: Pan T-, Pan B-, CD2+, 3-, 4-, 8-, 19-, 20-, 16-, 57-, HLA-DR+. Laboratory findings on admission indicated no abnormal findings. (Hb 13.9g/dl, Platelet 227, 000/μl, WBC 3, 600/μl with 0% abnormal lymphoid cells.) Anti-HTLV-1 antibody was negative. Bone marrow aspiration, chest X-P, abdominal echo, whole body CT revealed no abnormalities. He was diagnosed as cutaneous non-T, non-B cell lymphoma. Electoron beam therapy was effective for the skin lesion.In October, 1991, he visited us again, complaining of high fever and night sweating. His leukocyte count was found to be 1, 900/μl, with large granular lymphocyte occupying 15% of peripheral blood, and 85% of bone marrow.Large granular lymphocytes were characterized by a presence of azurophilic granules in the cytoplasm. Two color analysis was performed using the flow cytometric method, 75.4% of the cells from the bone marrow examined under that method proved to be double-positive for both CD2 and CD56. Tumor cells were found to have the expression of CD 2+, 3-, 8-, 16-, 56+, 57-. They did not rearrange (β, γ) T cell antigen receptor gene. Based on those findings, the case was finally diagnosed as cutaneous natural killer cell lymphoma accompanied with acute leukemia. Although a combination chemotherapy using MACOP-B was performed, the patient died of sepsis within four months after the start of the therapy. Natural killer cell leukemia is classified into two types; one type with good and mild prognosis, the other with a poor. The latter type is characterized by a symptom of high fever, hepatosplenomegaly and lymphnode swelling, and does not express CD16, 57. These findings suggest that the examination of the surface antigen on natural killer cell is necessary for the diagnosis of the lymphoma with skin lesion of increased large granular lymphocytes.