Keratoacanthoma-Type Invasive Squamous Cell Carcinoma Managed Non-surgically With Topical Immunomodulators

A rapidly growing lesion with keratoacanthoma-like features may complicate early diagnosis of squamous cell carcinoma (SCC). While most cutaneous SCCs exhibit slow, indolent growth, lesions with keratoacanthoma-like features may demonstrate more rapid expansion, occasionally complicating early diagnosis. We report a case of a 71-year-old male patient with a history of actinic keratoses and non-melanoma skin cancer who presented with a new blistering, erythematous eruption on the left dorsal forearm. A potassium hydroxide (KOH) prep revealed branching hyphae, and the patient was initially treated with oral antifungals. However, biopsy of the lesion confirmed a well-differentiated invasive SCC of keratoacanthoma type. Given the lesion's size and clinical behavior, the patient was referred for oncology-directed care and successfully treated with topical immunomodulation. PET imaging ruled out metastasis, and clinical resolution was observed on follow-up. This case underscores the diagnostic complexity of keratoacanthoma-like SCCs and highlights the need for biopsy in suspicious or atypical presentations. It also reflects evolving treatment approaches in select cases of cutaneous SCC, particularly among elderly patients with comorbidities or those who decline surgical management.