Clinical Challenge: Pigmented Plaque on the Upper Back

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A 37-year-old Hispanic woman seeks treatment for “bumps” on both arms and shoulders that were previously diagnosed as keratosis pilaris. Upon physical examination, a 1.2cm deeply pigmented and slightly raised plaque is observed on her upper back. She is aware of the lesion but uncertain as to how long it has been present or if it has changed in size recently. Her personal and family histories were negative for skin cancer, and she denied prior indoor tanning.

Blue nevi manifest as blue to black papules or nodules. The coloration is due to pigmented melanocytes within the mid-dermis that reflect blue light in accordance with the Tyndall effect.1 These ectopic melanocytes are postulated to result from incomplete migration from...

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Blue nevi manifest as blue to black papules or nodules. The coloration is due to pigmented melanocytes within the mid-dermis that reflect blue light in accordance with the Tyndall effect.1 These ectopic melanocytes are postulated to result from incomplete migration from the neural crest to the dermoepidermal junction.2

Histology reveals dermal proliferation of spindle cells and melanin pigment positive for HMB-45 (gp100), S-100 and Melan-A/MART-1 expression.3 Clinically, lesions may resemble melanoma. Dermoscopy and reflectance confocal microscopic examination are suggestive but should not be relied upon for diagnosis.4  Malignant transformation of an existing blue nevus into malignant blue nevus, a variant of malignant melanoma, is a rare occurrence.4

The median number of nevi in the Hispanic patient population is said to be somewhat lower than that for the Caucasian population,5 and in the United States Hispanic patients have 7 times lower melanoma incidence rates than non-Hispanic White patients.6 Still, greater skin cancer awareness within the Hispanic community has been advocated, especially since Hispanic patients have higher rates of thick melanoma (Breslow thickness ≥ 4 mm) at time of diagnosis.7

Stephen Schleicher, MD, is director of the DermDox Center for Dermatology in Pennsylvania, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College. 

References

  1. Oliveira AHK, Shiraishi AFMC, Kadunc BV, Sotero PC, Stelini RF, Mendes C. Blue nevus with satellitosis: case report and literature reviewAn Bras Dermatol. 2017;92(5 Suppl 1):30-33. doi:10.1590/abd1806-4841.20175267
  2. Suchniak JM, Griego RD, Rudolph AH, Waidhofer W. Acquired multiple blue nevi on an extremityJ Am Acad Dermatol. 1995;33(6):1051-1052. doi:10.1016/0190-9622(95)90319-4
  3. Daltro LR, Yaegashi LB, Freitas RA, Fantini BC, Souza CD. Atypical cellular blue nevus or malignant blue nevus?An Bras Dermatol. 2017;92(1):110-112. doi:10.1590/abd1806-4841.20174502
  4. Fei WM, Li CX, Cui Y. Diagnostic value of dermoscopy combined with reflectance confocal microscopy for clinically equivocal blue nevusChin Med J (Engl). 2020;133(17):2116-2118. doi:10.1097/CM9.0000000000001007
  5. Andreeva VA, Cockburn MG. Cutaneous melanoma and other skin cancer screening among Hispanics in the United States: a review of the evidence, disparities, and need for expanding the intervention and research agendasArch Dermatol. 2011;147(6):743-745. doi:10.1001/archdermatol.2011.140
  6. Kamath S, Miller KA, Cockburn MG. Current data on risk factor estimates does not explain the difference in rates of melanoma between Hispanics and Non-Hispanic Whites. J Skin Cancer. 2016;2016:2105250. doi:10.1155/2016/2105250
  7. Robinson JK, Joshi KM, Ortiz S, Kundu RV. Melanoma knowledge, perception, and awareness in ethnic minorities in Chicago: recommendations regarding educationPsychooncology. 2011;20(3):313-320. doi:10.1002/pon.1736

This article originally appeared on Clinical Advisor