Becker naevus associated with basal cell carcinoma, melanocytic naevus and smooth-muscle hamartoma

Blue nevus with smooth muscle hyperplasia: A rare hamartoma

A limited number of distinct histopathological variants of blue nevus exist, and hamartomatous proliferations involving melanocytic components, dendritic, or otherwise, have also been described. Blue nevus/smooth muscle hamartomas represent a rarely described entity. In this paper, we add two examples of this unusual hamartoma to the existing literature. These additional blue nevus/smooth muscle hamartomas occurred on the left mid-upper back of a 50-year-old woman and the central upper back of a 54-year-old man. Both lesions were clinically atypical pigmented lesions. Histopathologic review of both specimens revealed proliferations of predominantly spindled and pigmented dermal melanocytes with associated smooth muscle hyperplasia, compatible with blue nevus/smooth muscle hamartoma. Both specimens were accompanied by subtle changes suggesting follicular induction, a phenomenon previously described as occurring in a minority of specimens. A brief re-examination of recently diagnosed blue nevus at our institution did not reveal any additional cases in which a subtle smooth muscle component had been missed, suggesting this type of hamartoma is, indeed, exceedingly rare.

Sebaceus and Becker's Nevus: Overview of Their Presentation, Pathogenesis, Associations, and Treatment

Nevus sebaceus (NS) and Becker's nevus (BN) are two variants of epidermal nevi. NS clinically presents as a yellowish-orange, hairless plaque on the scalp, face, or neck, while BN presents as a tan-to-brown hyperpigmented, sometimes hypertrichotic, plaque typically on the chest and shoulder. Histologically, NS displays mature or nearly mature sebaceus glands as well as acanthosis and fibroplasia of the papillary dermis. BN shows variable papillomatosis, acanthosis, and hyperkeratosis, with hyperpigmentation of the basal/suprabasal layer. While the genetic basis of NS is thought to be due to post-zygotic mutations in the Harvey rat sarcoma viral oncogene homolog (HRAS)/Kristen rat sarcoma viral oncogene homolog (KRAS) genes, the genetic basis of BN is relatively unknown and is implicated with paradominant inheritance. In some patients, NS and BN can each be associated with additional cutaneous and extra-cutaneous anomalies, ranging from benign or malignant tumors to multiple organ irregularities. Due to the wide range of possible associations, treatment for NS and BN is devised on a case-by-case basis. In this article, we review the features, etiology, and diagnosis/management of NS and BN, with a focus on associations. We also report a patient who concomitantly presents with both lesions.

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

BACKGROUND

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

METHODS

We review the clinicopathological features of 12 cases of combined blue nevi with smooth muscle hyperplasia.

RESULTS

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).

CONCLUSION

We present an unusual hamartoma with features of combined blue nevus and smooth muscle hyperplasia, which has not been previously described.

Epidermal nevi

Nevi or nests of cells may be made up of a variety of cell types. The cell types that live in the epidermis include epidermal cells or keratinocytes, sebaceous glands, hair follicles, apocrine and eccrine glands, and smooth muscle cells. This article discusses epidermal or keratinocyte nevi, nevus sebaceous, nevus comedonicus, smooth muscle hamartomas, and inflammatory linear verrucous epidermal nevi. Syndromes associated with epidermal nevi are also reviewed.