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. 2011 Jan;56(1):79-81.
doi: 10.4103/0019-5154.77559.

Giant melanoacanthoma mimicking malignant melanoma

Vikas Shankar  1 , Jayoti Nandi, Kisalay Ghosh, Sanjay Ghosh
Affiliations

Giant melanoacanthoma mimicking malignant melanoma

Vikas Shankar et al. Indian J Dermatol. 2011 Jan.

Abstract

Melanoacanthoma denotes a rare variant of pigmented seborrheic keratosis. A 65-year-old male farmer had pigmented, verrucous, itchy, highly painful, progressively growing irregularly oval plaque on left side of lower back for the past five years. The indurated lesion, measuring maximum diameter 10 cm × 5 cm, had no discharge, bleeding, ulceration, or associated lymphadenopathy. Dermoscopy showed regular pigmentary network and cribiform pattern of ridges without any feature of malignant melanoma. Histopathology showed well-defined islands of basaloid cells interspersed with large and richly dendritic melanocytes. The lesion was totally excised followed by skin grafting. Our patient was unique in its massive size and clinical resemblance with malignant melanoma. The diagnosis was confirmed by dermoscopy and skin biopsy.

Keywords: Melanoacanthoma; dermoscopy; malignant melanoma; melanoma; pigmented seborrheic keratosis; seborrheic keratosis.

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Conflict of interest statement

Conflict of Interest: Nil.

Figures

Figure 1
Figure 1
Oval lesion of maximum transverse diameter 10 cm having brown to blackish pigmentation, well-defined margin and verrucous surface
Figure 2
Figure 2
Dermoscopy showing regular pigmentary network without any suggestive features of malignant melanoma like brown globules, black dots, pseudopods, or depigmentation. Cribriform patterns of ridges are seen.
Figure 3
Figure 3
The basaloid cells formed well-defined islands and numerous melanocytes were scattered throughout the lesion (H&E stain: 400×)
See this image and copyright information in PMC

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