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Presentation
Case Findings: A 68-year-old farmer presents for evaluation of a painless, solitary nodule that rapidly developed on his left fourth finger 3 weeks ago.- There was no antecedent trauma and he denies joint pain, swelling, or altered range of motion.
- He feels well otherwise, with no fevers or constitutional symptoms.
What is your diagnosis?
1382% Giant molluscum contagiosum
2625% Sporotrichosis
1132% Prurigo nodule
3974% Keratoacanthoma
801% Mycetoma
1255% Cutaneous metastasis
Keratoacanthomas are neoplasms considered to be a sub-type of squamous cell carcinomas that develop rapidly as solitary, painless lesions on sun-exposed skin with a characteristic crateriform appearance. The lesions are almost always large nodules with a central keratin-filled cup, resembling a “volcano†on the skin. Left untreated, some keratoacanthomas spontaneously involute and resolve leaving an atrophic scar; however, as keratoacanthomas are a type of squamous cell carcinoma, treatment is recommended. Patients will rarely present with multiple, eruptive keratoacanthomas, and keratoacanthomas have been described to arise within scars or sites of skin injury, including following attempted, incomplete removal of individual keratoacanthomas. Keratoacanthomas have been reported to occur in the setting of some medications, including new targeted therapies for metastatic melanoma (the BRAF-inhibitor class of drugs).
Management & Therapy Tips
- Keratoacanthomas are sub-type of squamous cell cancer with a distinct clinical appearance, which develop rapidly and may self resolve.
- As a type of squamous cell, most keratoacanthomas warrant treatment.
- Surgical excision, intralesional chemotherapy (such as with methotrexate, 5-fluorouracil, or in some cases bleomycin), or other destructive modalities may be employed.
- In patients with multiple, eruptive keratoacanthomas, consider evaluating for a potential trigger, including a new medication, although this is quite rare.
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