A 73-year-old man is referred for evaluation of a skin lesion on his upper back. The patient is uncertain how long the lesion has been present. He denies itching, burning, or bleeding associated with the lesion. He states that he smokes cigarettes and consumes alcohol in moderation. Examination of the lesion reveals a 1.5-cm, hyperpigmented, hyperkeratotic plaque. Scattered seborrheic keratoses are noted elsewhere on the patient’s body. Axillary and cervical lymph nodes are nonpalpable.
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Squamous cell carcinoma (SCC) is the second most common nonmelanoma form of skin cancer, representing approximately 20% of cases.1 Approximately 1 million new cases of SCC are diagnosed each year in the United States.1,2 SCC is more common among older adults, and lesions most frequently arise on sun-exposed areas of the body. SCC may arise de novo or from a precursor lesion such as an actinic keratosis. Advanced tumors characteristically present as hyperkeratotic plaques and nodules. Metastases are uncommon, occurring in 3.7% to 5.2% of patients; overall mortality is between 1.5% and 2.1%.3
Histologic variants of SCC include spindle cell, verrucous, acantholytic, desmoplastic, basaloid, and pigmented subtypes.4 Pigmented cutaneous SCC is rare, and the majority of cases occur within the oral and ocular mucosa.5 Differentiation of pigmented SCC from other pigmented neoplasms such as melanoma may be difficult.6 The presence of pigmentation has no bearing on course or prognosis.
Shereen Timani, MD, is a board-certified dermatologist and dermatopathologist, and is director of Johns Creek Dermatology in Johns Creek, Georgia. 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.
1. Waldman A, Schmults C. Cutaneous squamous cell carcinoma. Hematol Oncol Clin North Am. 2019;33(1):1-12.
2. Rogers HW, Weinstock MA, Feldman SR, Coldiron BM. Incidence estimate of nonmelanoma skin cancer (keratinocyte carcinomas) in the US population, 2012. JAMA Dermatol. 2015;151(10):1081-1086.
3. Thompson AK, Kelley BF, Prokop LJ, Murad MH, Baum CL. Risk factors for cutaneous squamous cell carcinoma recurrence, metastasis, and disease-specific death: a systematic review and meta-analysis. JAMA Dermatol. 2016;152(4):419-428.
4. Paolino G, Donati M, Didona D, Mercuri SR, Cantisani C. Histology of non-melanoma skin cancers: an update. Biomedicines. 2017;5(4):71.
5. Satter EK. Pigmented squamous cell carcinoma. Am J Dermatopathol. 2007;29(5):486‐489.
6. de Morais PM, Schettini APM, Rocha JA, da Silva Júnior RC. Pigmented squamous cell carcinoma: case report and importance of differential diagnosis. An Bras Dermatol. 2018;93(1):96‐98.