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.