Answer of Dermatopathology Case 59

Pigmented Spindle Cell Nevus of Reed.

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Abstract

Hypopigmented Reed nevus.J Cutan Pathol. 2008 Oct;35 Suppl 1:87-9. Epub 2008 Jun 28.

Reed nevus, also named pigmented spindle cell nevus, is a peculiar melanocytic nevus, now regarded as a variant of Spitz nevus by the majority of authors. It is characterized by spindle-shaped melanocytes disposed in nests located in epidermis and papillary dermis. It is usually heavily pigmented, and many melanophages may also be present. Hypopigmented Reed nevus shows all the typical features of conventional pigmented spindle cell nevus, but it does not contain abundant melanin. This variant of Reed nevus is poorly described in literature, so we report five cases of hypopigmented Reed nevus and discuss its clinical and histopathological features.

Epithelioid and hyperpigmented melanocytic tumors. An overview. Pathologe. 2007 Nov;28(6):411-21.

Spindle cell and epithelioid cell differentiation occur in both benign and malignant hyperpigmented melanocytic lesions. Reed nevus is characterized by compact, sharply circumscribed junctional cellular nests composed of slender hyperpigmented melanocytes shaped like spindle cells. Deep penetrating nevus is characterized by a diffuse dermal proliferation composed of small nests and fascicles of pale ovoid and epithelioid melanocytes. Cellular blue nevi often have a characteristic hourglass or dumbbell shape, with sharply circumscribed elongated nests and fascicles of pale, densely layered ovoid melanocytes and adjacent melanophages. Epithelioid blue nevus is characterized by large epithelioid melanocytes with abundant cytoplasm and melanin often concentrated to some degree in the cell membrane. Animal-type melanoma is a particularly hyperpigmented variant of melanoma in which large melanophages predominate and there are varying proportions of melamin-rich spindle-shaped and large atypical epithelioid melanocytes. Morphologically, pigmented epithelioid melanocytoma combines characteristics of both animal-type melanoma and pigmented epithelioid nevus. Malignant melanoma may occur in conjunction with a preexistent blue nevus. Malignant blue nevus is now regarded as a malignant melanoma mimicking a blue nevus in structure and pattern. It is therefore of paramount importance to view multiple mitoses within a cellular blue nevus-like proliferation as an alarm signal as they are usually indicators of a malignant melanoma.

Melanocytic nevi simulant of melanoma with medicolegal relevance.Virchows Arch. 2007 Sep;451(3):623-47. Epub 2007 Jul 26.

A group of melanocytic benign nevi are prone to be misdiagnosed as nodular or superficial spreading melanoma. This review illustrates the most frequent forms of these nevi in direct comparison with their malignant morphologic counterparts. The nevi are: hyper-cellular form of common nevus to be distinguished from nevoid melanoma, Spitz nevus (vs spitzoid melanoma), Reed nevus (vs melanoma with features of Reed nevus), cellular atypical blue nevus (vs melanoma on blue nevus), acral nevus (vs acral melanoma), Clark dysplastic nevus (vs superficial spreading melanoma), desmoplastic nevi (vs desmoplastic melanoma), benign proliferative nodules in congenital nevi (vs melanoma on congenital nevi), epithelioid blue nevus (vs animal type melanoma) and regressed nevus (vs regressed melanoma). For each single 'pair' of morphological look-alikes, a specific set of morphological, immunohistochemical and genetic criteria is provided.

Pigmented spindle cell nevus: a clinicopathologic analysis of ninety-five cases. J Am Acad Dermatol.1993 Apr;28(4):565-71.

BACKGROUND: Pigmented spindle cell nevus (PSCN) is often interpreted as a Spitz nevus or misdiagnosed as malignant melanoma.
OBJECTIVE: The purpose of this study was to analyze the clinical and histologic features and to determine the biologic behavior of 95 cases of PSCN.
METHODS: We reviewed clinical data, follow-up information, and microscopic features of all 95 cases of PSCN.
RESULTS: PSCNs are dark brown to black, 3 to 6 mm in diameter, and occur most commonly on the extremities (75%) and back (16%) with a predilection for the legs. These lesions are more common in women in the third decade of life. Microscopically, PSCNs are characterized by uniform, spindle-shaped, pigmented melanocytes. Although some histologic features overlap with those in spindle and epithelioid cell nevus, PSCN is a separate entity. In addition, PSCN must be differentiated from malignant melanoma. Fifty-seven patients (60%) observed for an average of 6 years did not develop local recurrence or metastasis.
CONCLUSION: PSCN is a distinctive, acquired, benign melanocytic lesion, that should not be confused with spindle and epithelioid cell nevus or malignant melanoma. Complete excision is recommended for treatment.

Pigmented spindle cell nevus. Clinical and histologic review of 90 cases. Am J Surg Pathol.1984 Sep;8(9):645-53.

A clinical and histologic review of 90 patients with melanocytic lesions termed pigmented spindle cell nevi (PSCN) is reported. The lesions are small in surface diameter, sharply confined both clinically and histologically, and often occur on the proximal extremities of young adults. They are generally of recent onset, moderately to heavily pigmented, and made up of nests of spindled cells confined to the epidermis and papillary dermis. There were 30 male and 60 female patients. Their average age was 25.3 years (ranging from 2.5 to 56 years). Lesions were located on the extremities in 61 cases (67%). Follow-up was possible in 38 cases seen more than 6 months after histologic diagnosis and ranged up to 40 months (average 14 months). No local recurrence or distant spread was found. The importance of recognizing this lesion lies in differentiating it from malignant melanoma. Conservative but complete excision has resulted in no recorded instances of local recurrence or distant spread.

The pigmented spindle cell tumor of Reed: an underdiagnosed lesion.Semin Diagn Pathol.1987 Feb;4(1):75-87.

The pigmented spindle cell tumor is a distinct benign melanocytic lesion with characteristic clinical and histopathologic features. Until recently, it has been poorly documented in the literature and is frequently misdiagnosed as malignant melanoma. On the basis of 40 personal cases of pigmented spindle cell tumor, the clinical and pathologic features of the lesion and its differential diagnosis will be discussed.