Comparison of the Inflammatory Infiltrates in Tumoral Melanosis, Regressing Nevi, and Regressing Melanoma.

BACKGROUND: Tumoral melanosis (TM) is a histologic diagnosis characterized by abundant pigment-laden macrophages in the dermis. It is generally thought to represent a regressed melanoma, although it has also been reported after benign pigmented lesions as well. Determining the antecedent lesion in cases of TM is of clinical importance to accurately guide therapy and prognostication. Comparing the histopathologic and immunohistochemical (IHC) characteristics of TM, halo nevi (HN), and regressing melanoma (RM) may help predict the antecedent lesion in cases of TM. METHODS: Cases of TM, HN, and RM were selected and assessed for histopathologic (preservation of junctional melanocytic component, depth and width, solar elastosis, fibrosis, and preservation of rete ridge architecture) and IHC (SOX-10, CD138, and PD-1) parameters. PD-L1 immunostaining was also evaluated in cases of HN and RM. RESULTS: Severe solar elastosis, fibrosis, and marked rete ridge effacement were more frequent in RM than in HN. By contrast, numerous plasma cells, clusters of lymphocytes expressing PD-1, and >50% PD-L1 expression in melanocytes were more common in HN than in RM. However, the association of these variables did not reach statistical significance. DISCUSSION: Although studies with higher statistical power are needed, this study serves as an initial investigation to characterize the histopathologic and IHC characteristics, which may help better understand TM and its precursor lesions.

Cutaneous Squamous Cell Carcinoma: Review of the Eighth Edition of the American Joint Committee on Cancer Staging Guidelines, Prognostic Factors, and Histopathologic Variants.

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.

Superficial malignant peripheral nerve sheath tumor with overlying intradermal melanocytic nevus mimicking spindle cell melanoma.

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.

Desmoplastic Melanoma: Clinical Behavior and Management Implications.

INTRODUCTION: Desmoplastic melanoma is a rare variant of melanoma that has been reported to demonstrate unique clinical behavior when compared with other histological subtypes. In this study, we present the clinical course of patients with this unusual diagnosis. We hypothesized that desmoplastic melanoma would differ from nondesmoplastic melanoma with regard to its presentation, rate of regional metastasis, and recurrence pattern. METHODS: After institutional review board approval, a retrospective chart review was performed on all patients with a diagnosis of desmoplastic melanoma since 1998. The following data were collected: patient demographics, histopathological details of the lesion, initial treatment, and clinical course. In addition, the available slides were reviewed by a dermatopathologist. RESULTS: Twenty-eight patient charts were reviewed. Mean age at diagnosis was 65 years. Fifty-seven percent of patients were men, and 67% of the lesions originated from the head and neck. Of the 28 patients, 11 had pathology slides that were adequate for evaluation. Pure desmoplastic melanoma, defined by more than 90% of the specimen demonstrating desmoplastic features, was found in only 3 patients. Taking into account all cases, the mean Breslow thickness was 5.09 mm and ulceration was present in 12.5% of lesions. Regional disease was discovered in 18% of patients. The mean follow-up time was 43 months, and the overall recurrence rate was 32%. 66.7% of first recurrences were local. Two of 3 patients with pure desmoplastic melanoma developed regional metastasis. CONCLUSIONS: Our data largely support previous studies that suggest desmoplastic melanoma behaves differently compared with other histological subtypes. However, the incidence of regional disease among patients with pure desmoplastic melanoma appears to be higher in our study than in previous reports. Although this rare variant typically presents with advanced local disease, the rate of regional metastasis is less than what would be expected for similar thickness, nondesmoplastic cutaneous melanoma. The recurrence pattern is different compared with nondesmoplastic melanoma, and the most common site of recurrence is local. Discrepancy in the literature regarding the clinical behavior of this disease may be related to inconsistent pathological criteria for diagnosis. Further research will help clarify the optimal management of desmoplastic melanoma.

Lesions of the lacrimal caruncle with an emphasis on oncocytoma.

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.