Cutaneous sarcomatoid carcinoma with features of giant cell tumor of soft parts--a case report

Two Cases of Cutaneous Sarcomatoid Squamous Cell Carcinoma Resembling Cutaneous Giant Cell Tumor of Soft Tissue

ABSTRACT

Cutaneous sarcomatoid squamous cell carcinoma is well-described with histology resembling pleomorphic undifferentiated sarcoma featuring collagenous or myxoid stroma with or without elements of keratinizing squamous carcinoma. This report presents 2 cases of dedifferentiated squamous cell carcinoma (SCC) composed of sheets of malignant mononuclear cells with malignant osteoclast-like multinucleated giant cells, extravasated blood, and hemosiderin resembling cutaneous giant cell tumor (cGCT). In the first case, an exophytic facial mass of a 96-year-old woman removed by shave showing extensive cGCT-like tumor but with microscopic elements of SCC in situ and positivity for cytokeratin 5/6 in the malignant spindle cells and SCC. The second case involved a 32-year-old man with a pedunculated penile mass removed by shave biopsy, displaying malignant cytology resembling cGCT, focal staining for cytokeratin AE1/AE3 and p63, and CD68 highlighting the osteoclast-like giant cells. Molecular analysis revealed CDKN2A, TP53, and TERT. Upon reexcision, case 2 showed focally invasive keratinizing SCC associated with differentiated penile intraepithelial neoplasia and lichen sclerosus. Skin specimens with an exophytic mass histologically resembling cGCT but with malignant cytology should be meticulously evaluated for elements of SCC. Molecular analysis, detecting mutations like H3F3 or HMGA2-NCOR2 fusion, can aid in distinguishing cutaneous sarcomatoid squamous cell carcinoma from GCT bone or GCT soft tissue.

Osteoclast-like giant cell reaction associated with cutaneous squamous cell carcinoma: a report of 2 cases and review of the literature

The observation of osteoclast-like giant cells (O-LGCs) in intimate association with visceral malignancies is an uncommon phenomenon that has been recognized for over 40 years. Recently, the same observation has been made in relation to cutaneous malignancies. In an article published in 2005, O-LGCs were documented in association with 3 melanomas, and since then, there have been 3 separate case reports recording the presence of these cells in cutaneous carcinomas. In the context of both visceral and cutaneous malignancies, the exact nature of the O-LGCs has been a source of controversy, with respect to whether they represent modified tumor cells or an unusual host response to the neoplasm. We report here 2 additional cases of cutaneous squamous cell carcinoma associated with O-LGCs. The morphological pattern of the giant cell proliferation differed between these cases, taking the form of (1) a giant cell tumor-like nodule apposed to the carcinoma in one and (2) scattered O-LGCs interspersed with tumor cells in the other. Based on scrutiny of routine sections and the contrasting immunohistochemical profiles of the O-LGCs versus the carcinomas, showing CD68 positivity on one hand and high-molecular weight keratin and p63 positivity on the other, we concluded that in both instances, the O-LGC proliferation was a reactive phenomenon. This theory is supported by most publications on the subject. Clinical and histopathological details of the new cases are outlined and integrated with those in the literature.