Combined Melanocytic Nevus Research Articles

Combined Melanocytic Nevus and Nevus Sebaceus: A Case Series and Review of the Literature.

Nevus sebaceus is a rare congenital hamartoma with clinical and histopathological features that change with puberty. It has been associated with a number of secondary neoplasms, most of which are thought to derive from follicular germ cells. In this article, the authors describe a total of 3 cases of combined melanocytic nevus and nevus sebaceus to highlight this rare finding.

Cutaneous epithelioid melanocytic neurofibroma arising in a patient with neurofibromatosis‐1

Tumors expressing both melanocytic and neural features can pose a diagnostic challenge to the dermatopathologist and provoke questions regarding their lineage. We report a case of a tumor arising on the right cheek of a 9-year-old boy with neurofibromatosis type 1 (NF-1). This neoplasm featured nests of non-pigmented epithelioid cells arising within a neurofibroma. The entire tumor stained strongly with S100, whereas the epithelioid population stained with MART-1, HMB-45 and MiTF. The neoplasm shows only scattered Ki-67 positivity. This tumor represents a neurofibroma with portions that have undergone melanocytic differentiation (melanocytic neurofibroma). This exceedingly rare tumor represents a distinct entity from neurotized melanocytic nevi, combined melanocytic nevi or pigmented neurofibromas and provides further evidence that melanocytes arise indirectly from ventromedial neural crest-derived Schwann cell precursors.

Combined blue nevus‐smooth muscle hamartoma: a series of 12 cases

One of the most common types of combined melanocytic nevus is that of a blue nevus with ordinary melanocytic nevus. Blue nevi have also been described in association with non-melanocytic cell types, such as those of neural or mesenchymal derivation. Although there are rare descriptions in the literature of blue nevi with myomatous structures, the specific association of combined blue nevi with smooth muscle hyperplasia has not been reported We review the clinicopathological features of 12 cases of combined blue nevi with smooth muscle hyperplasia. The majority of these lesions occurred on the back of middle-aged patients and were clinically interpreted as melanocytic nevi or melanoma. Histopathologic examination revealed a combined population of 'common' and blue nevus melanocytes with accompanying smooth muscle hyperplasia. In addition to a lentiginous proliferation of melanocytes at the dermal-epidermal junction with variable basilar hyperpigmentation, there were varying degrees of epidermal acanthosis and follicular induction (three cases). We present an unusual hamartoma with features of combined blue nevus and smooth muscle hyperplasia, which has not been previously described.

Rosette-like structures in the spectrum of spitzoid tumors

Spitz nevi demonstrate a diverse spectrum of morphologies. Recently, there have been two reported examples of Spitz nevi with rosette-like structures similar to Homer-Wright rosettes. Rosettes have also been described in melanomas and in a proliferative nodule arising in a congenital nevus. A retrospective review of 104 cases of Spitz nevi and variants (n = 51), pigmented spindle cell nevi (n = 26), combined melanocytic nevi with features of Spitz (n = 8), atypical Spitz tumor (AST, n = 9), and spitzoid melanoma (n = 10). Rosette-like structures were present in 3 of the 104 cases (2.9%), including a compound Spitz nevus, a desmoplastic Spitz nevus, and an AST. All three cases demonstrated several foci of small nests of epithelioid cells with peripherally palisaded nuclei arranged around a central area of fibrillar eosinophilic cytoplasm. Immunohistochemical staining of the three spitzoid lesions demonstrated that the rosette-like structures express S100 protein, Melan-A, and neuron specific enolase (NSE) and lacked expression of neurofilament, glial fibrillary acidic protein and synaptophysin. While uncommon, rosette-like structures can occur as a focal feature in Spitz nevi and AST. Rosette-like structures may represent a normal morphologic finding in Spitz nevi, and awareness of them may prevent misdiagnosis as a neural tumor or melanoma.

Congenital Combined Melanocytic Nevus of the Scalp With Associated Alopecia Areata

We report a case of a 20-year-old Chinese man with an alopecic congenital combined compound and blue melanocytic nevus of the scalp, associated with alopecia areata. The diagnosis of a combined melanocytic nevus was confirmed by histopathological examination and immunohistochemical stains, with exclusion of neurocristic hamartoma, which can have a similar clinical and histopathological appearance but different prognosis. In addition, we explore the association of this large melanocytic lesion with alopecia areata.

Combined BRAFV600E-positive Melanocytic Lesions With Large Epithelioid Cells Lacking BAP1 Expression and Conventional Nevomelanocytes

Recently a group of spitzoid melanocytic proliferations with loss of BAP1 expression has been reported. The lesions may occur sporadically or as part of a familial cancer syndrome. They have distinct histopathologic features characterized by a nevus-like silhouette and cytologic composition of large epithelioid melanocytes with oval vesicular nuclei, distinct nucleoli, and abundant cytoplasm with well-defined cytoplasmic borders. A characteristic immunohistochemical finding is loss of nuclear labeling for BAP1. In contrast to classic Spitz nevi, the lesions carry the BRAF mutation. They may present as a pure large epithelioid cell proliferation or as a combined lesion in association with a conventional nevus. Here we report a series of 8 combined melanocytic lesions, in which a dominant large epithelioid cell proliferation with loss of BAP1 expression was associated and intimately admixed with a BAP1-positive conventional nevus. These biphenotypic lesions were from 6 patients, 3 female and 3 male, ranging in age from 16 to 59 years. Immunohistochemical analysis for BAP1 showed loss of nuclear labeling confined to the large epithelioid melanocyte subpopulation. The conventional melanocytes retained BAP1 expression. Both large epithelioid and conventional melanocytes were immunoreactive with the monoclonal antibody VE1, which recognizes the protein encoded by mutant BRAF. In 6 cases the conventional nevus component was a compound nevus of small "type B" melanocytes. In 2 cases, the nevus remnant was entirely intradermal. The lesions described herein may represent a peculiar combined melanocytic nevus variant. However, longer follow-up and more studies are needed to determine the biological potential of the BAP1-negative melanocyte proliferations.

Combined melanocytic nevus presenting with scalp alopecia associated with alopecia areata: Coincidence or causal?

Combined melanocytic nevus presenting with scalp alopecia associated with alopecia areata: Coincidence or causal?

Melanocytic Lesions: Current State of Knowledge—Part II

Melanocytic Lesions: Current State of Knowledge—Part II

Dermoscopic features of combined melanocytic nevi.

In order to investigate the possible role of dermoscopy in the non-invasive classification of combined nevi, we analyzed dermoscopic features of a series of combined nevi consecutively excised. Two dermatologists expert in dermoscopy retrospectively evaluated all images based on the presence of dermoscopic findings to analyze which epiluminescence microscopy features were more frequently associated with each type of combined nevus. Dermoscopy may provide useful information in the non-invasive diagnosis of combined nevi, allowing a conservative management, but this may be limited to combined nevi including a blue nevus component. Conversely, combined nevi including a Spitz nevus component may be difficult to classify even by dermoscopy, thus requiring careful monitoring or surgical excision.

A combined variant of Spitz's nevi. How to differentiate them from malignant melanomas.

In the past several years we have studied 22 lesions of what we believe are combined variants of Spitz's nevi. Almost all of the patients were young adults. These combined melanocytic nevi have the architectural pattern of benign lesions, i.e., they are relatively symmetrical and well circumscribed. Each was characterized by the presence of at least two populations of nevus cells, one relatively banal with small nuclei and scant cytoplasm, the other with large nuclei and abundant cytoplasm. The latter are indistinguishable from cuboidal (epithelioid) cells of Spitz's nevus. The banal and the large nevus cells were intermingled in some of the lesions, but were segregated in others. Because these combined nevi differ from conventional Spitz's nevi and because the large nevus cells often fail to show maturation with progressive descent into the dermis, they are commonly misdiagnosed histologically as malignant melanomas.