Cutaneous squamous cell carcinoma is the second most common form of nonmelanoma skin cancer after basal cell carcinoma and accounts for the majority of nonmelanoma skin cancer-related deaths. In 2017, the American Joint Committee on Cancer revised the staging guidelines of cutaneous squamous cell carcinoma to reflect recent evidence concerning high-risk clinicopathologic features. This update reviews the literature on prognostic features and staging, including the eighth edition of the American Joint Committee on Cancer Staging Manual. A wide range of histopathologic variants of cutaneous squamous cell carcinoma exists, several of which are associated with aggressive behavior. A review of cutaneous squamous cell carcinoma variants, emphasizing diagnostic pitfalls, immuhistochemical findings and prognostic significance, is included. Of note, the eighth edition of the American Joint Committee on Cancer Staging Manual refers to squamous cell carcinoma of the head and neck only.
Malignant peripheral nerve sheath tumors are rare soft tissue sarcomas with histological and immunohistochemical similarities to spindle cell melanoma. Although spindle cell melanoma is significantly more common, both tumors may express S100 and lack staining for HMB-45, Melan-A or MITF. Here we present a case of superficial malignant peripheral nerve sheath tumor with diffuse S100 positivity arising in a subtle neurofibroma in close proximity to an intradermal melanocytic nevus. This configuration had led to prior misdiagnosis as a desmoplastic melanoma arising in the nevus and to sentinel lymph node biopsy. Identification of the background neurofibroma, as well as CD34 positivity raised consideration of a low grade malignant peripheral nerve sheath tumor, which was confirmed via observation of Schwannian differentiation on electron microscopy. The importance of distinguishing these two tumors is stressed owing to the difference in management.
Lesions of the lacrimal caruncle vary widely due to its unique composition. Rarely, dermatologists and dermatopathologists encounter biopsies taken from this location. The aims of this study were to (1) retrospectively review caruncular lesions of the eye examined at Duke University Medical Center and (2) review the literature associated with caruncle pathology with emphasis on oncocytoma. A retrospective search of all lesions of the caruncle examined at Duke University Medical Center from 1991 to 2009 was performed. Fifty-nine lesions of the caruncle were identified. Nevi (40.7%) were the most common lesions observed, although squamous papillomas were the second most common entity (8.5%). Three oncocytomas were identified (5.1%), and were the next most common lesion present at this body site. These 3 entities represented 54.3% of the lesions found in the caruncle. Fifteen percent of the caruncular biopsies contained malignant or borderline malignant lesions, whereas the remaining 85% were benign entities. Most lesions present in the caruncle are benign. Although relatively rare, oncocytomas may be encountered by the dermatopathologist and may be confused for other neoplasms. Oncocytomas should be considered in the differential diagnosis based on this location in addition to histopathologic features.
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