Non-melanocytic mimics of melanoma, part II: intradermal mimics

Tong, Leung Chu; Kamil, Zaid Saeed; Habeeb, Ayman Al; Ghazarian, Danny

doi:10.1136/jcp.2008.062927

Cited by 14 publications

(4 citation statements)

References 126 publications

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“…Accordingly, melanomas may rarely resemble reactive or neoplastic histiocytic lesions, including benign and malignant fibrous histiocytoma, atypical fibroxanthoma, dermatofibrosarcoma protuberans, Langerhans cell histiocytosis, reticulohistiocytoma and xanthogranuloma . Similarly, histiocytic proliferations including Langerhans cell histiocytosis and xanthoma have been uncommonly confused with melanoma .…”

Section: Discussionmentioning

confidence: 99%

Metastatic melanoma with balloon/histiocytoid cytomorphology after treatment with immunotherapy: A histologic mimic and diagnostic pitfall

et al. 2018

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Epithelioid cells with foamy cytoplasm (histiocytoid features) are typical histopathologic findings among benign and malignant histiocytic neoplasms such as xanthoma and atypical fibroxanthoma. However, these changes are unusual in melanoma, which is typically composed of nested and variably pigmented atypical epithelioid cells. Here, we report a patient with metastatic melanoma in lymph nodes presenting with prominent balloon cell/histiocytoid features expressing melanocytic markers, after treatment with nivolumab. This report suggests that the spectrum of neoplasms with histiocytoid features should be expanded to include melanoma, a pattern that, to the best of our knowledge, is uncommon, especially in the setting of post-neoadjuvant therapy.

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Section: Discussionmentioning

confidence: 99%

Metastatic melanoma with balloon/histiocytoid cytomorphology after treatment with immunotherapy: A histologic mimic and diagnostic pitfall

et al. 2018

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“…20,35 The cellular features of neoplastic melanocytes may therefore closely mimic those of poorly differentiated malignant neoplasms, including carcinomas, soft tissue sarcomas, and round cell neoplasms such as lymphomas. 15,20,27,31,35,39 The combined lack of pigmentation and the indistinct cellular morphology of many oral malignant melanomas in particular often make definitive diagnosis difficult, if not impossible, when based on microscopic examination alone. It is, however, of the utmost importance to accurately diagnose and differentiate canine oral melanocytic neoplasms from other poorly differentiated neoplasms, given that prognosis and therapy vary greatly between the differentials.…”

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confidence: 99%

Immunohistochemical Diagnosis of Canine Oral Amelanotic Melanocytic Neoplasms

et al. 2010

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Definitive diagnosis of canine oral melanocytic neoplasms is often difficult because of variability in pigmentation and cellular pleomorphism. These neoplasms can resemble carcinomas, sarcomas, and round cell neoplasms, which differ in prognosis and treatment. A variety of immunohistochemical antibodies have been used for diagnosis of melanocytic neoplasms in humans and dogs; however, sensitivity and specificity of many markers have not been determined in amelanotic melanocytic neoplasms in dogs. The authors investigated a comprehensive panel of immunohistochemical markers in 49 canine oral amelanotic melanocytic neoplasms-namely, Melan-A, PNL2, HMB-45, microphthalmia transcription factor (MiTF), S-100, tyrosine hydroxylase, tyrosinase, tyrosinase-related proteins 1 and 2 (TRP-1 and TRP-2), and CD34. Ten well-differentiated cutaneous soft tissue spindle cell sarcomas were negative controls. Melan-A, PNL2, TRP-1, and TRP-2 were highly sensitive and 100% specific for the diagnosis of canine oral amelanotic melanocytic neoplasms. S-100 and MiTF showed high sensitivity but were less specific; that is, they also labeled a proportion of the soft tissue spindle cell sarcomas. HMB-45, tyrosinase, and tyrosine hydroxylase were 100% specific but had low sensitivities. CD34 did not label any of the melanocytic neoplasms but did label 80% of the soft tissue spindle cell sarcomas. A cost-effective and efficient immunodiagnostic cocktail containing antibodies against PNL2, Melan-A, TRP-1, and TRP-2 was created that had 100% specificity and 93.9% sensitivity in identifying canine oral amelanotic melanocytic neoplasms. The spindloid variant was the variant with the lowest sensitivity to the cocktail. The likelihood of correctly diagnosing canine oral amelanotic melanocytic neoplasms was dramatically higher when biopsy samples contained ample overlying and adjacent epithelium.

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“…Antibodies that are key to differentiating melanomas include S-100, HMB-45, MART-1, and MiTF. 26 Immunohistochemistry is often necessary for a definitive diagnosis of melanomas because of their ability to be the ''great pretender.'' In a retrospective study of 48 feline melanoma cases, Melan-A and S-100 positive staining was found in 67.0% and 88.5% of these masses, respectively.…”

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confidence: 99%

Amelanotic Melanoma in a New Zealand White Rabbit (Oryctolagus cuniculus)

et al. 2010

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A 3.5-year-old intact male double-transgenic New Zealand white rabbit (Oryctolagus cuniculus), apoA-I and LCAT (apolipoprotein and lecithin:cholesterol acyltransferase), was presented with a discrete, raised facial mass (0.5 Â 1.0 Â 1.0 cm). The mass was surgically excised, with reoccurrence to the same site 88 days later. A second surgical excision was performed, and the rabbit died 3 weeks later from respiratory distress. At necropsy, multiple varying-sized masses were observed in the ventral mandibular region and throughout the lungs, pleura, and diaphragm. On histopathology, the masses were composed of moderately anisocytotic and anisokaryotic polygonal to spindloid cells with moderate finely granular, lightly eosinophilic cytoplasm, having round to oval nuclei with one to several nucleoli and finely stippled chromatin. Mitotic figures were frequent. Lymphatic and venous invasion were noted with neoplastic cells metastasized to the submandibular lymph nodes, lungs, liver, and adventitial surface of the aorta. Fontana-Masson stain was negative for melanin, thereby necessitating immunohistochemistry and transmission electron microscopy. Positive staining with MART-1 (a melanocyte protein marker) combined with transmission electron microscopy revealing type II melanosomes confirmed the diagnosis of an amelanotic melanoma.

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Non-melanocytic mimics of melanoma, part II: intradermal mimics

Cited by 14 publications

References 126 publications

Metastatic melanoma with balloon/histiocytoid cytomorphology after treatment with immunotherapy: A histologic mimic and diagnostic pitfall

Metastatic melanoma with balloon/histiocytoid cytomorphology after treatment with immunotherapy: A histologic mimic and diagnostic pitfall

Immunohistochemical Diagnosis of Canine Oral Amelanotic Melanocytic Neoplasms

Amelanotic Melanoma in a New Zealand White Rabbit (Oryctolagus cuniculus)

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