Malignant Cutaneous Adnexal Tumor in Posterior Occipital Region of a Child: A Case Report

Abstract

Introduction: The most common cutaneous adnexal tumors in children were follicular, especially pilomatricoma, and a few were predominant glandular/ductal differentiation, malignant forms are occasionally encountered. Here, a case of a malignant cutaneous adnexal tumor with eccrine differentiation was reported. Case presentation: A 10-year-old male child was presented with a nodular in posterior occipital for half a year with no symptoms. Histopathology showed there was acanthosis in epidermis, partially with local ulceration and crusting; and in the dermis, there was irregular scattered or agglomerated infiltration of diffused epithelial cells, partly presenting as basaloid, but no obvious peripheral palisading arrangement; and in the center there was extensive necrosis; cellular pleomorphism, scattered mitotic figures, focal clear cell areas, and adenoid differentiation can also be seen, there was scattered infiltration of mixed inflammatory cells in the stroma. Immunohistochemistry showed cytokeratin (CK) 5/6+, CK 8/18+, epithelial membrane antigen +, gata3 transcription factor 3+, cell adhesion15 (focal +), Ki67 (+, 30%), carcinoembryonic antigen (focal+), CK 7 (focal+), gross cystic disease fluid protein-15−, P63+, S-100−. Final diagnosis was the malignant cutaneous adnexal tumor with eccrine differentiation, most likely the nodular clear cell hidradenocarcinoma. The patient has no special discomfort follow-up observation after extended resection and lymph node examination. Discussion: The histopathology showed infiltrative growth pattern, deep extension, necrosis, nuclear pleomorphism, mitoses, desmoplastic stromal reaction and the clear cell area and adenoid differentiation. Immunohistochemistry was positive for CK8/18, EMA, CK5/6, P63, gata3 transcription factor 3 and negative for S-100 and GCDFP-15, some gland-derived markers such as CK7, CEA were focal positive, and we have not found the preexisting benign poroma and porocarcinoma in situ, so we preferred the diagnosis of hidradenocarcinoma. The differential diagnosis such as porocarcinoma, clear cell squamous cell carcinoma, and basal cell carcinoma were taken into account. Conclusion: The diagnosis was challenging by clinical manifestations. Histopathology and immunohistochemistry should be combined with clinical presentation, history to reach the final diagnose.