Cellular Blue Nevus

INTRODUCTION Cellular blue nevus is a variant of the common blue nevus, but was first described as a variant of melanoma. Although these can be similar clinically to the common blue nevus, they tend to be larger, elevated, and have more pronounced celluarity composed of nonpigmented spindle-shaped melanocytes. They are most common in Asian populations, and rare in blacks. The cellular blue nevus is believed to represent a dermal arrest of embryonal migration of neural crest melanocytes that fail to reach the epidermis. They tend to remain unchanged throughout life, but there have been rare reports of malignant transformation to melanoma.

CLINICAL PRESENTATION Cellular blue nevus can appear at any age but generally develops in the second decade of life or later. They start out as singular smooth surfaced flat macules that slowly develop into dome-shaped papules. Color varies from gray-blue to bluish black. The dark color results from their deep location in the dermis and the Tyndall effect where differential absorption of long wavelengths of light and scattering of short wavelengths by melanin favors the blue end of the spectrum. Malignant change is heralded by a sudden increase in size and occasional ulceration.

Oculodermal Melanocytosis

HISTOPATHOLOGY Lesions are usually well circumscribed and composed of nests and interweaving fascicles of mostly non-pigmented spindle-shaped melanocytes having pale cytoplasm. Melanophages may be found between the cellular islands. The presence of melanin-containing dermal

Spindle Cell Carcenoma

melanocytes interspersed with the non-pigmented cells aids in differentiating the lesion from other spindle-cell tumors such as dermatofibroma or leiomyoma. The melanocytic nature of the process may be confirmed immunohistochemically since the cells express S-100 protein and HMB-45.

DIFFERENTIAL DIAGNOSIS The differential diagnosis includes melanocytic nevus, oculodermal melanocytosis, malignant melanoma, and dermatofibroma.

TREATMENT A biopsy is indicated for any change in size or pigmentation. Malignant degeneration can occur in part of the lesion so that it can be missed on routine biopsy. When therapy is indicated for cosmesis or for malignant change, surgery is necessary. For small lesions simple excision is curative. Larger lesions can be infiltrative into eyelid tissues and the orbit making complete excision difficult.

REFERENCES

Barnhill RL, Barnhill MA, Berwick M, Mihm MC Jr. The histologic spectrum of pigmented spindle cell nevus: a review of 120 cases with emphasis on atypical variants. Hum Pathol 1991; 22:52-58.

Gunduz K, Shields JA, Shields CL, Eagle RC Jr. Periorbital cellular blue nevus leading to orbitopalpebral and intracranial melanoma. Ophthalmology 1998; 105:2046-2050.

Rodriguez HA, Ackerman LV. Cellular blue nevus. Clinicopathologic study of forty-five cases. Cancer 1968; 21:393-405.

Temple-Camp CR, Saxe N, King H. Benign and malignant cellular blue nevus. A clinicopathological study of 30 cases. Am J Dermatopathol 1988; 10:289-296.

Tran TA, Carlson JA, Basaca PC, Mihm MC. Cellular blue nevus with atypia (atypical blue nevus): a clinicopathologic study of nine cases. J Cutan Pathol 1998; 25:252-258.

Zembowicz A, Granter SR, McKee PH, Mihm MC. Amelanotic cellular blue nevus: a hypopigmented variant of the cellular blue nevus; clinicopathologic analysis of 20 cases. Am J Surg Pathol 2002; 26:1493-1500.

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Responses

  • John
    How does a cellular blue naevus start?
    6 years ago

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