Cutaneous mixed tumor, eccrine variant: a clinicopathologic and immunohistochemical study of 50 cases, with emphasis on unusual histopathologic features.

Mixed tumor, eccrine type, is a rare cutaneous adnexal neoplasm, mostly reported as isolated case reports. A systematic analysis of its histopathologic and immunohistochemical features has not previously been performed on a large series. The purpose of our investigation was to study a large number of cutaneous eccrine mixed tumors so as to fully characterize the entire spectrum of changes in the epithelial and stromal components, with an emphasis on unusual histopathologic features that may represent a diagnostic pitfall. This article reports a light microscopic and immunohistochemical study of 50 cases of eccrine mixed tumor, complemented by a literature review. Our study identified some unusual histopathologic features, thus extending the morphologic spectrum of this neoplasm. These included prominent cribriform areas, clear cell change, pseudorosette structures, prominent osseous metaplasia, and physaliphorous-like cells. Most of these features have not been previously recorded in eccrine mixed tumors and may represent a potential diagnostic pitfall.

[Malignant melanoma masquerading as a neurotrophic ulcer]. / Malignes Melanom imitiert ein neurotrophes Ulkus.

CASE REPORT: A 77-year-old female patient with an ulceration of the heel is described, which was treated over a period of 2 years as a neurotrophic ulcer related to diabetes mellitus. After the initial examination in the outpatient wound healing clinic, a malignant melanoma already showing invasive growth with a penetration depth of 4.6 mm was detected in a biopsy. After diagnosis and exclusion of metastases, a phase-adapted complete excision was carried out. Furthermore, an adjuvant immunotherapy was introduced. CONCLUSION: Malignant melanoma is a primary cutaneous malignant tumor. Its thickness at the time of the initial diagnosis is crucial to the prognosis. Ulcerated and amelanotic melanomas still present a considerable clinical challenge due to the likelihood of being mistaken for benign diseases and the occurrence of filiae when diagnosis is made too late. This case report demonstrates the importance of differential diagnostic consideration of neoplasias, for example malignant melanoma, in cases of unclear, therapy-refractory wounds and discusses the relevant aspects in avoiding an unnecessary prolongation of diagnostics.