“Keratoacanthoma is a skin lesion that erupts in sun damaged skin, rather like a little volcano. It grows for a few months, then will usually shrink and resolve by itself. Keratoacanthoma is considered to be a variant of the keratinocytic or non-melanoma skin cancer, squamous cell carcinoma (SCC). Since it cannot be clinically reliably distinguished from more serious forms of skin cancer, keratoacanthomas are usually treated surgically.”
Most older dermatologists recognize keratoacanthomas (KAs) clinically. However, the trend these days is for dermatopathologists to label KAs “squamous cell carcinoma, well-differentiated.” This makes sense since dermatopathologists want to cover their bets, but it leaves the patient with a malignant diagnosis. KA, in the past, was also known as “benign self-healing epithelioma.” Since procedure codes for malignant lesions are higher than for benign ones, most clinicians will happily code these lesions as malignant when, in reality, the majority were destined to behave benignly.
Reference: Keratoacanthoma: A distinct entity?
Gleich T, et. al. Exp Dermatol. 2015 Oct 17. doi: 10.1111/exd.12880.
Abstract: Keratoacanthoma (KA) are common but exceptional benign tumors, often appearing on sun-exposed areas of light skinned people and showing spontaneous resolution. The goal of this study was to review existing literature, to point out the etiologic complexity of KA biology and to answer the controversial debate if or not KA is a distinct entity or a variant of squamous cell carcinoma (SCC). Relying on recent results, we highlight that KA is an individual lesion with a unique molecular signature caused by alterations in the TGFβ signaling pathway. These recent findings will help to understand the nature of KA and to develop new reliable diagnostic tools, simplifying the discrimination of the histologically similar KA and SCC.