Ann Dermatol.  2017 Jun;29(3):327-330. 10.5021/ad.2017.29.3.327.

Acral Lentiginous Melanoma, Indolent Subtype Diagnosed by En Bloc Excision: A Case Report

• Ohn J
• Bae JM
• Lim JS
• Park JS
• Yoon HS
• Cho S
• Park HS

• KMID: 2378533
• DOI: http://doi.org/10.5021/ad.2017.29.3.327

Abstract

Nail unit melanoma is a type of acral lentiginous melanoma and requires histopathologic examination for a confirmed diagnosis. However, inadequate biopsy techniques make definitive diagnosis difficult. A 61-year-old man presented with progressive nail pigmentation for 15 years, which was clinically highly suspicious for malignancy. Acral lentiginous melanoma was not detected in punch and longitudinal biopsy specimens, but en bloc excision tissue revealed melanoma. Acral lentiginous melanoma is known to have a heterogeneous pathologic manifestation depending on the pigmented region and the time it takes to progress. In this regard, en bloc excision can be considered as a first-line biopsy technique to diagnose acral lentiginous melanoma, indolent subtype.

Keyword

Acral lentiginous melanoma; Biopsy; Melanoma; Melanonychia; Nails; Subungual melanoma

MeSH Terms

Biopsy
Diagnosis
Humans
Melanoma*
Middle Aged
Pigmentation

Figure

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  Fig. 1 (A) Dark black colored pigmented band with about 1-cm width on the left thumbnail. Ulceration, onychodystrophy, and Hutchinson's sign were observed. (B) Left lateral portion of the nail unit was longitudinally biopsied, enclosing nail folds, hyponychium, and nail matrix.

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  Fig. 2 (A) Prominent pigmentation in the nail plate without atypical melanocytes (H&E; ×100, inset: ×50). (B) Bland pigmentation was in the basal layer of hyponycium (H&E; ×100, inset: ×10). (C) Significant pigmentation was observed in the nail bed without atypical melanocytes (H&E; ×400, inset: ×100).

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  Fig. 3 (A) Two months later, the nail unit presented with plate destruction and intermittent bleeding from the nailbed. (B) En bloc excisional specimen of the nail unit. (C) Scattered pigmentation was observed in the hyponychium and the nail bed with lymphocytic infiltration in the onychodermis layer (H&E, ×10). (D) Atypical melanocytes with hyperchromatic nuclei invaded the dermis layer (H&E, ×100). (E, F) Immunohistochemical stains for human melanoma black 45 and Ki-67 were positive (×100).

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