Skin melanocytic tumor
Melanocytic tumors on acral skin and nail apparatus
Subungual melanoma (melanoma of the nail apparatus)
Author: Christopher S. Hale, M.D.
Last author update: 1 May 2013
Last staff update: 3 November 2020
Copyright: 2002-2024, PathologyOutlines.com, Inc.
PubMed Search: Subungual melanoma
Table of Contents
Definition / general | Epidemiology | Sites | Clinical features | Case reports | Treatment | Dermoscopy | Clinical images | Microscopic (histologic) description | Microscopic (histologic) images | Differential diagnosisCite this page: Hale CS. Subungual melanoma (melanoma of the nail apparatus). PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumormelanocyticsubungualmelanoma.html. Accessed April 23rd, 2024.
Definition / general
- Melanoma arising in nail unit
Epidemiology
- Uncommon; difficult to diagnose clinically and pathologically
- Median age 66 years (Am J Surg 2008;195:244), range 24 to 83
Sites
- Common sites are great toe and thumb
Clinical features
- Often delay in diagnosis because lesion is attributed to trauma; most (73%) cases are AJCC stage II / III, acral lentiginous subtype (66%) and Clark level IV / V (79%, Am J Surg Pathol 2007;31:1902)
- Sentinel node metastases in 24%
Case reports
- 86 year old man with posttraumatic amelanotic tumor (Dermatol Online J 2008;14:13)
- Regressed tumors (Dermatol Surg 2006;32:577)
- With osteocartilaginous differentiation (Skeletal Radiol 2003;32:724)
- Amelanotic tumor resembling pyogenic granuloma (J R Coll Surg Edinb 2002;47:638)
Treatment
- Wide local excision, may require amputation (Am J Surg 2008;195:244) although conservative approach for thumb lesions has been advocated (J Plast Reconstr Aesthet Surg 2007;60:635)
Dermoscopy
- Useful for distinction from subungual hemorrhage
- Features include: Hutchinson sign, longitudinal irregular lines, triangular shape of bands, vascular pattern and ulcerations (Br J Dermatol 2013;168:1224)
Clinical images
Images hosted on other servers:
Red, friable, broad based nodule
Ulcer on left middle finger
Microscopic (histologic) description
- Usually not circumscribed
- Have prominent lentiginous growth with more single cells than nests, moderate to severe atypia, haphazard and dense pagetoid intradermal spread
- Also ulceration (33%), tumor infiltrating lymphocytes
Microscopic (histologic) images
Images hosted on other servers:
Tumor cells are isolated or in nests
Tumor cells are MelanA+
Differential diagnosis
- Lentigo
- Fungal melanonychia
- Minocycline induced pigmentation
- Subungual hemorrhage
