A 73-year-old man presents to the dermatology clinic for evaluation of hand dermatitis. During the physical examination, scattered keratoses are noted on his face, and a triangular erythematous patch is identified on his upper chest. The patient was unaware of the duration of the patch and denies trauma to the area, itching, and/or bleeding. No similar patches are noted elsewhere.
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Shave biopsy of the chest lesion revealed superficial basal cell carcinoma. Superficial and nodular basal cell carcinomas are considered low-risk neoplasms compared with the micronodular, morpheaform, infiltrative, and basosquamous types.1 The superficial variant represents approximately 20% of these tumors and unlike most basal cell carcinomas occurs predominantly on the trunk and extremities.2 When detected early, superficial basal cell carcinomas can be cured with treatment. Treatment modalities include topical medications (fluorouracil and imiquimod), surgery (ie, excisional and Mohs surgery), cryotherapy, photodynamic therapy, and radiotherapy.3
Geometrically shaped malignant skin lesions as opposed to those that are round or ovoid are infrequently described in the literature. Even apparently benign lesions with a geometric shape may pose a risk of malignant disease.4 Geometrically shaped lesions are more commonly encountered in cases of dermatitis artefacta.5
Stephen Schleicher, MD, is director of the DermDox Center for Dermatology, as well as an associate professor of medicine at Commonwealth Medical College and a clinical instructor of dermatology at Arcadia University and Kings College.
1. Shamsi-Meymandi S, Dabiri S, Zeynadini-Meymand A, et al. Evaluation of immunohistochemical findings and clinical features associated with local aggressiveness in basal cell carcinoma. Iran J Pathol. 2019;14(3):193-196.
2. van Delft LCJ, Nelemans PJ, Jansen MHE, et al. Histologic subtype of treatment failures after noninvasive therapy for superficial basal cell carcinoma: an observational study. J Am Acad Dermatol. 2019;80(4):1022-1028.
3. Fukumoto T, Fukumoto R, Oka M, Horita N. Comparing treatments for basal cell carcinoma in terms of long-term treatment-failure: a network meta-analysis. J Eur Acad Dermatol Venereol. 2019;33(11):2050-2057.
4. Morris AD, Gee BC, Millard LG. Geometric cutaneous melanoma: a helpful clinical sign of malignancy? Dermatol Surg. 2003;29(8):827-828.
5. Ngan V. Dermatitis artefacta, DermNet NZ website. https://www.dermnetnz.org/topics/dermatitis-artefacta/. Published 2003. Accessed November 13, 2019.