Colonization of nonmelanocytic cutaneous lesions by dendritic melanocytic cells: a simulant of acral-lentiginous (palmar-plantar-subungual-mucosal) melanoma

Uncommon Pigmented Carcinoma In Situ: Case Report and Brief Review

Pigmented lesions of the oral mucosa encompass several benign and malignant conditions that may be a matter of concern under both clinical and histopathological views. We reported a case of a 62-year-old woman, presenting with an asymptomatic, deeply pigmented lesion on the soft palate. On examination, it appeared asymmetrical, with irregular borders and an area of ulceration. A biopsy, taken to rule out melanoma, revealed a pigmented carcinoma in situ. Throughout the tumor thickness, numerous interspersed melanocytes were found that did not extend to neighboring epithelium. These were large, richly dendritic, and presented abundance of melanin granules and small nuclei. Mild melanin incontinence was found. Scanty transfer of pigment to dysplastic epithelial cells was found through Fontana Masson staining. On immunohistochemical analyses, there were pancytokeratin-stained tumor epithelial cells; increased cell proliferation throughout the entire thickness of the tumor was emphasized by Ki-67 immunomarking. P16 was negative. The dendritic cells were selectively stained for S-100, HMB45 and Melan A. Wide spectrum in situ hybridization for human papillomavirus (HPV) was negative. Unfortunately, following diagnosis, the patient refused any treatment option. Pigmented squamous cell carcinoma with melanocyte colonization must be taken into account in the differential diagnosis of pigmented lesions of the oral cavity.

Non-melanocytic mimics of melanocytic neoplasms

On histopathologic examination, many non-neoplastic conditions mimic benign or malignant neoplasms. Alternatively, some benign and malignant neoplasms can also mimic non-neoplastic lesions. This is true of all organ systemsskin is no exception. Examples of these mimickers can be found in skin lesions of almost all tissue types, including those that are melanocytic, lymphoid, epithelial, neural, vascular, neuroendocrine, and fibrohistiocytic. Melanocytic neoplasms are particularly important as it's challenging to differentiate them as being benign or malignant, and it's difficult to tell them apart from non-melanocytic neoplasms. This review illustrates examples of non-melanocytic lesions that disguise themselves as melanocytic.

Pigmented Squamous Cell Carcinoma

Although dendritic, melanin-containing melanocytes can be seen in a variety of epithelial neoplasms, only 0.01% to 7% of all squamous cell carcinomas (SCC) are pigmented. Furthermore, most reported cases have occurred in the oral and ocular mucosa, with relatively few cases reported to originate in the skin. Herein we report a case of a 61-year-old Caucasian male who presented with a large blue-black nodule on his left cheek, clinically suspicious for a melanoma; however, histological evaluation revealed an acantholytic pigmented squamous cell carcinoma. Previous cases are reviewed and the clinical and histological differential diagnoses are discussed.

Melanocytic colonization of a meningothelial meningioma: histopathological and ultrastructural findings with immunohistochemical and genetic correlation: case report

OBJECTIVE AND IMPORTANCE

Melanocytic colonization of nonpigmented extracranial tumors has been reported in adenocarcinomas, squamous cell carcinomas, skin appendage tumors, and dermatofibrosarcoma protuberans. To our knowledge, melanocytic colonization of a meningioma has not previously been described.

CLINICAL PRESENTATION

We report an unusual case of a 70-year-old African-American woman who presented with a large frontoparietal meningioma that extended through the calvarium.

INTERVENTION

Craniotomy with gross total resection of the tumor was performed. Histochemistry, immunocytochemistry, ultrastructural analysis, and molecular genetic study via fluorescence in situ hybridization confirmed melanocytic colonization of a meningothelial meningioma.

CONCLUSION

With the inclusion of meningothelial meningioma, the spectrum of tumors affected by melanocytic colonization continues to expand.

Pigmented squamous cell carcinoma with dendritic melanocyte colonization in the external auditory canal

A case of pigmented squamous cell carcinoma (SCC) with dendritic melanocyte colonization in the external auditory canal is reported and the previous cases are reviewed. A 65-year-old Japanese female was referred with a 7-year history of otitis. The patient also had a darkly pigmented 9 x 8 mm nodule in the external auditory canal. Microscopically, the tumor was SCC, but in some areas melanin pigments were found in the cytoplasm of the tumor cells. The tumor was thus diagnosed as pigmented SCC. As well as the tumor cells, dendritic-shaped cells colonized the tumor parenchyma and were immunohistochemically defined as melanocytes. The authors believe this is the first case of pigmented SCC with dendritic melanocyte colonization in the external auditory canal.

Dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans is a tumor of intermediate malignancy characterized by its aggressive local growth and marked propensity to recur after surgical excision. This article reviews the incidence, clinical presentation, histologic features, immunocytochemical studies, histogenesis, prognosis, management, and follow-up recommendations for this unusual neoplasm.

Soft tissue sarcomas in dermatology

BACKGROUND

Dermatofibrosarcoma protuberans, atypical fibroxanthoma, and cutaneous leiomyosarcoma are uncommon soft tissue sarcomas that tend to have a high recurrence rate when removed with standard excisional surgery, and in some cases have been reported to metastasize. These tumors have been reported in the surgical, medical, and pathology literature. The diagnosis and treatment of these tumors is still evolving. Wide excision and surgical techniques involving meticulous surgical margin control appear to be the most efficacious treatment for these problematic tumors.

OBJECTIVE

The surgical, medical, and pathology literature was extensively reviewed to collate the observations of multiple investigators, and to summarize their findings. Literature from medical journals of multiple subspecialties as well as textbooks were reviewed with particular emphasis on diagnosis, histologic features including immunohistochemistry, and useful surgical techniques that facilitate the removal of these difficult tumors.

RESULTS

Dermatofibrosarcoma protuberans is a soft tissue neoplasm of intermediate malignancy that shows a high recurrence rate when treated with standard excision. Wide surgical excision using a 3-cm margin greatly reduces the risk of recurrence, but is not practical in some cases. Evidence is continuing to accumulate that Mohs micrographic surgery may be the treatment of choice for this tumor. Atypical fibroxanthoma is best thought of as a superficial form of malignant fibrous histiocytoma. It is histologically indistinguishable from certain forms of malignant fibrous histiocytoma and differs primarily in its size and superficial location. These tumors are best removed surgically. For most smaller tumors a 1-cm margin, which is carried down to the subcutaneous tissue, provides adequate treatment. In cases where tissue conservation is important, Mohs micrographic surgery has been shown to be very effective. Cutaneous leiomyosarcoma is a rare superficial soft tissue sarcoma that has a high incidence of recurrence after excision and can metastasize. Because of the small number of patients treated, treatment recommendations are still evolving. Currently, wide local excision is recommended with a 3-5 cm margin and removal of the underlying subcutaneous tissue. Mohs micrographic surgery has been used in a small number of cases with good success.

CONCLUSION

Dermatofibrosarcoma protuberans, atypical fibroxanthoma, and cutaneous leiomyosarcoma are soft tissue sarcomas that have a high rate of recurrence when treated with standard surgical techniques and may occasionally metastasize. When removing these tumors it is very important to take adequate margins. Mohs micrographic surgery is proving to be very useful in treating these difficult neoplasms.

Oral melanoacanthoma with prominent spongiotic intraepithelial vesicles

Oral melanoacanthoma is a rarely-reported, benign pigmented lesion of oral mucosa. Spongiosis was only recently mentioned as a light-microscopical finding occasionally seen in oral melanoacanthoma, and the formation of spongiotic intraepithelial vesicles to our knowledge has never been reported. The authors discuss a case of a 34-year-old, black woman who acutely developed extensive hyperpigmented oral lesions which on the biopsy showed both intraepithelial dendritic melanocytes and severe spongiosis forming intraepithelial vesicles. These lesions resolved spontaneously in a few months which led the authors to believe that the term melanoacanthoma, implying that it is a tumor, is a misnomer. This report supports findings of other investigators who consider oral melanoacanthoma to be a mucositis with unusual proliferation of dendritic melanocytes in the epidermis.

Dermatofibrosarcoma non-protuberans: description and report of five cases of a morpheaform variant of dermatofibrosarcoma

Five cases of dermatofibrosarcoma are reported. All showed features typical of dermatofibrosarcoma protuberans except that in four cases, and a portion of the fifth case, no protusion of the tumor was noted clinically despite the rather advanced stage of growth of the tumor. These lesions resembled morphea or a morpheaform basal cell carcinoma clinically but could be recognized as "dermatofibrosarcoma non-protuberans" by physicians who had observed a previous case.