Don’t Just Look at the Lesion

DISCUSSION
The biopsy results confirmed the impression of superficial squamous cell carcinoma (SSC) with focal areas of invasion.

One thinks of skin cancer as being “a thing,” a papule or nodule, and that’s usually true. But there are several types of skin cancer that manifest as a fixed rash—meaning it stays in the same place year after year, unlike other rashes (eg, psoriasis, eczema, or fungal infection). Common examples, besides superficial SCC (also known as Bowen disease), include superficial basal cell carcinoma (BCC), Paget disease (mammary and extramammary), cutaneous T-cell lymphoma, and even local recurrence of breast cancer.

This patient’s occupation and history of (abundantly evident) sun damage put him at risk for a sun-caused skin cancer. As so often happens, the problem was initially misdiagnosed by a provider who was only looking at the lesion instead of factoring in the context in which it appeared. Who has the lesion is almost as important as the lesion itself.

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Without a biopsy, Bowen disease is often indistinguishable from superficial BCC; the latter can take on a variety of appearances, from scar-like (cicatricial) to pigmented (especially in patients with darker skin) to the most common, nodular/noduloulcerative. Another item in the differential is discoid lupus erythematosus, particularly when the lesion manifests in a highly sun-exposed area.

Treatment of this patient’s lesion entailed full excision with 3-mm margins. This option was chosen based on the focal areas of invasion and theoretical potential for metastasis.

TAKE-HOME LEARNING POINTS

• Intraepidermal squamous cell carcinoma (Bowen disease) presents as a red, scaly rash with a rounded, well-demarcated border, almost always on skin directly overexposed to the sun.
• These cancers grow slowly, are fixed in location, never heal, and—given enough time—often become focally invasive.
• They will often be misdiagnosed as fungal infection, psoriasis, or eczema, because of the misperception that skin cancers are always papular or nodular.
• A history of sun exposure and resulting markers of dermatoheliosis serve to corroborate the putative diagnosis.