Unusual variants of malignant melanoma

Harvard University, Cambridge, Massachusetts, United States
Modern Pathology (Impact Factor: 6.19). 03/2006; 19 Suppl 2(Suppl 2):S41-70. DOI: 10.1038/modpathol.3800516
Source: PubMed


A potential diagnostic pitfall in the histologic assessment of melanoma is the inability to recognize unusual melanoma variants. Of these, the more treacherous examples include the desmoplastic melanoma, the nevoid melanoma, the so-called 'minimal-deviation melanoma,' melanoma with prominent pigment synthesis or 'animal-type melanoma,' and the malignant blue nevus. Also problematic are the unusual phenotypic profiles seen in vertical growth phase melanomas; these include those tumors whose morphological peculiarities mimic cancers of nonmelanocytic lineage and those melanomas that express aberrant antigenic profiles not commonly associated with a melanocytic histogenesis. Metaplastic change in melanoma, balloon cell melanoma, signet-ring cell melanoma, myxoid melanoma, small cell melanoma and rhabdoid melanoma all have the potential to mimic metastatic and primary neoplasms of different lineage derivations. Abnormal immunohistochemical expression of CD 34, cytokeratins, epithelial membrane antigen, and smooth muscle markers as well as the deficient expression of S100 protein and melanocyte lineage-specific markers such as GP100 protein (ie HMB-45 antibody) and A103 (ie Melan-A) also present confusing diagnostic challenges. In this review, we will discuss in some detail certain of these novel clinicopathologic types of melanoma, as well as the abnormal phenotypic expressions seen in vertical growth phase melanoma.

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    • "The most important clue to the diagnosis of animal-type melanoma is effacement of the dermal architecture by areas of confluent melanocytic growth. Mitotic activity is usually very low 11. In our case, all the cells had low-grade pleomorphic nuclei, with nucleoli seen in some cells. "
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    ABSTRACT: We present a patient with an animal-type malignant melanoma associated with the nevus of Ota in the orbit who showed a good prognosis after a combination of orbital extirpation, chemotherapy, stereotactic radiotherapy, and gamma knife. A 42-year-old Japanese woman presented with two tumors, one pathologically diagnosed as right-sided intraconal animal-type malignant melanoma and the other intracranially, presumed to be of the same pathogenesis and both were considered to have arisen from the nevus of Ota. She underwent an extirpation of the orbit, chemotherapy (DAV therapy, which is a combination of dacarbazine, nimustine, and vincristine), stereotactic radiotherapy (54 Gy in 27 fractions), and gamma knife (marginal dose was 17 Gy, target volume was 0.2 ml). She has been alive for 33 months since the extirpation, with no sign of local recurrence, new metastasis, nor enlargement of the intracranial tumor. Not just combination therapy but also the low malignancy of animal-type melanoma may have contributed toward the good prognosis.This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.
    Full-text · Article · Mar 2014 · Melanoma research
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    • "Balloon cell melanoma (BCM) was first described in 1970 [2] and it has actually been described as the rarest melanoma subtype [3]. The prognosis appears to be related to Breslow thickness as with melanoma subtypes in general [1,4], but presumably because BCM tends to be thick at the time of presentation, the mortality rate is reported to be high. In the largest study, 19 of 33 (57.5%) patients with follow-up data died of disseminated disease 2 months to 12 years after initial treatment [1]. "
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    ABSTRACT: Balloon cell melanoma is a rare melanoma subtype, with only one previous case with dermatoscopy published. It is often non-pigmented, leading to diagnostic difficulty, and there is a tendency for lesions to be thick at diagnosis. We report a case of balloon cell melanoma on the forearm of a 61-year-old man with both polarized and non-polarized dermatoscopy and dermatopathology. It presented as a firm pale nodule with focal eccentric pigmentation. The clinical images evoke a differential diagnosis of dermatofibroma, dermal nevus, Spitz nevus and basal cell carcinoma as well as melanoma. This melanoma was partially pigmented due to a small, pigmented superficial spreading component on the edge of the non-pigmented balloon cell nodule, prompting further evaluation. In retrospect there was the clue to malignancy of polarizing-specific white lines (chrysalis structures) and polymorphous vessels, including a pattern of dot vessels. The reticular lines exclude basal cell carcinoma, polarizing-specific white lines are inconsistent with the diagnosis of dermal nevus and their eccentric location is inconsistent with both Spitz nevus and dermatofibroma. Excision biopsy was performed, revealing a superficial spreading melanoma with two distinct invasive components, one of atypical non-mature epithelioid cells and the other an amelanotic nodular component, comprising more than 50% of the lesion, characterized by markedly distended epithelioid melanocytes showing pseudo-xanthomatous cytoplasmic balloon cell morphology. A diagnosis of balloon cell melanoma, Breslow thickness 1.9 mm, mitotic rate 3 per square millimeter was rendered. Wide local excision was performed, as was sentinel lymph node biopsy, which was negative.
    Full-text · Article · Jan 2014
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    • "In the first reported case [4] and several subsequent cases [3] the meta-static lesion has been initially misinterpreted. Dermatopathologically the differential diagnosis includes balloon cell change in benign nevi, clear cell sarcoma, clear cell meta-static renal cell carcinoma, basal cell carcinoma, squamous cell carcinoma, malignant clear cell acrospiroma, sebaceous carcinoma and clear cell dermatofibroma [6]. "
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    ABSTRACT: A case of balloon cell melanoma encountered in a primary care skin cancer practice in Melbourne, Australia is presented. The presenting lesion was 6 mm in diameter, ulcerated, non-pigmented and without any algorithmic clues to melanoma. However the presence of terminal hairs caused the clinician to suspect that it was melanocytic. The lesion was reported as a balloon cell melanoma, Clark level 4, Breslow thickness 2 mm with a mitotic index of 4 per square mm. This is an extremely rare melanoma subtype. Author DW has encountered only two cases in a career involving in excess of one million signed out dermatopathology reports. A search of the literature has not discovered any previously published dermatoscopy images of a balloon cell melanoma.
    Full-text · Article · Jul 2013
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