Malignant “animal-type” melanoma in a seropositive African man

Pigmented Epithelioid Melanocytomas and Their Mimics; Focus on Their Novel Molecular Findings

Simple Summary

Pigmented epithelioid melanocytoma (PEM) is a rare entity with a controversial biological behavior. Some of these tumors behave in an indolent manners while others can locally spread. Herein, we review the clinical presentations, the pathological features as well as the genomic signatures associated with this rare entity. We also report an example of a challenging case of PEM that we encountered and show how usage of novel molecular diagnostic techniques focusing helps addressing this diagnostic conundrum.

Abstract

Pigmented epithelioid melanocytoma (PEM) is a unique tumor with significantly pigmented appearance and indolent behavior; however, it can demonstrate cytological atypia and metastasize to local lymph nodes. Clinical and histomorphological overlap between PEM and its lower or higher-grade mimics can make it difficult to distinguish in certain cases. Genomic, transcriptomic and epigenetic data indicate that PEMs are molecularly distinct entities from other melanocytic neoplasms and melanomas. In addition, methylation studies are emerging as a tool that can be useful in difficult cases. In this review, we focus on the clinical, histopathologic and recent insights in the molecular features of pigmented epithelioid melanocytic melanocytomas and their mimics. We also present a challenging case that was resolved using methylation analysis providing a proof of concept for using epigenetic studies for similar challenging cases.

Animal-type melanoma: report of five cases with sentinel node biopsy and fluorescence in-situ hybridization analysis

Animal-type melanoma (ATM) is a rare tumor, characterized histologically by a predominantly dermal proliferation of heavily pigmented epithelioid and spindle dendritic melanocytes. Five patients with ATM, who had undergone sentinel node biopsy, were studied: three male and two female, between 4 and 62 years of age (mean, 28.0). Lesion size ranged from 4 to 18 mm and thickness from 0.7 to 5.1 mm. Nodal deposits were found in three patients. Of the patients with positive sentinel nodes, the first showed a minimal nodal involvement in one node, the second multiple deposits in one node, and the third multiple deposits in one sentinel node and a single deposit in another; this last patient also had additional tumor deposits in a nonsentinel regional node. Fluorescence in-situ hybridization tumor analysis proved negative in all cases. All patients are alive and free of disease at 36-95-month follow-up (mean, 53 months). Results showed ATM as a neoplasm characterized by a somewhat high rate of lymph node involvement but relatively low rate of visceral metastases and mortality, appearing as a low-grade malignant tumor.

Animal-type melanoma: clinical and dermoscopic features of 3 cases

Animal-type melanoma is a rare variant of malignant melanoma in humans. Although many patients develop locoregional and distant metastases, mortality is lower than in other types of melanoma. We present 3 cases of animal-type melanoma in elderly men and include a description of common clinical and dermoscopic features (homogeneous blue pattern, irregular whitish structures, and irregular large vessels).

[Melanoma in HIV patients: 14 cases]

BACKGROUND

a clinical study of 14 patients presenting both malignant melanoma and HIV infection, and analysis of the literature to determine the frequency and specific features of this association.

PATIENTS AND METHODS

ten men and four women of median age 43 years were included. In 50% of cases, the primary melanoma consisted of spreading superficial melanoma with a mean Breslow thickness of 2.83 mm. In two cases, regional lymph node metastasis was discovered but with no primary melanoma being identified. HIV infection was already documented on diagnosis of melanoma in 11 cases, and it was discovered in three cases at the time of surgery for melanoma (treatment of the primary melanoma in two cases, and in one case, regional lymph node dissection two years after the initial diagnosis). Eight patients died within a mean period of 39 months, with melanoma being the cause of death in six cases. Following relapse of melanoma, the course of the disease was severe, with mean stage IV survival of 3.6 months. No response to chemotherapy was observed where such treatment was feasible.

DISCUSSION

the presence of HIV appears to be an aggravating factor for the outcome of metastatic melanoma.

CONCLUSION

our study suggests the importance of clinical examination of pigmented lesions in HIV patients in order to ensure early identification of melanoma.

Animal-Type Melanoma: A Rare Type of Malignant Melanoma with an Indolent Clinical Behaviour

Animal-type melanoma is an exceedingly rare histological variant of melanoma in humans. The name was coined to reflect similar histological features to melanomas in grey horses. We present a case of animal-type melanoma. The neoplastic cells were heavily pigmented with an epithelioid morphology, round nuclei and prominent eosinophilic nucleoli. Only occasional mitotic figures were identified. The tumour cells had diffuse and nodular growth patterns with involvement of the dermis and the subcutaneous tissue. The patient had a “benign cellular blue naevus” excised 9 years earlier from the same site. Review of the previous case revealed heavily pigmented epithelioid cells with similar morphology to the current case. Nuclear pleomorphism was minimal and only a single mitotic figure was present. The lesion extended to the margins of excision. The diagnosis of animal-type melanoma was made on the current case and on the previously misdiagnosed case.

Recurrence of this case nine years following incomplete excision further supports the hypothesis that animal-type melanoma is a distinct histological type of malignant melanoma with an indolent clinical course.