Squamous Cell Carcinoma in the Diabetic Foot: A Review of Published Case Reports

Introduction Squamous cell carcinoma (SCC) is a malignant tumour arising from epidermal keratinocytes and is the second most common form of skin cancer globally. Although relatively rare on the foot, SCC and its variants may occur in people with diabetes and can mimic common diabetes-related foot ulcerations. This diagnostic overlap presents a risk of delayed recognition and treatment. The aim of this review was to synthesise published case reports of SCC occurring in the diabetic foot and to describe patient characteristics, clinical presentation, and outcomes.

Methods A review of case reports was conducted in accordance with the PRISMA guidelines. Electronic databases (Medline, CINAHL, SPORTDiscus and SCOPUS) were searched up to September 2025 using relevant terms for SCC and its variants. Studies describing clinical cases of SCC arising on the foot in individuals with diabetes were included.

Results Thirty-one cases from 13 countries were included. The mean age of patients was 62 years, with a predominance of males (71.0%) and type 2 diabetes (64.5%). Lesions most affected the right foot (64.5%) and were frequently located on the toes or plantar surfaces. The mean lesion duration prior to diagnosis was 61.9 months (range 2–360; n = 25). Initial misdiagnosis was most commonly as a foot ulcer (54.8%), followed by a wart (19.4%) and osteomyelitis (12.9%). Final diagnoses included SCC (51.7%), verrucous carcinoma (35.5%), and Marjolin's ulcer (12.9%). Pain was reported in 58.1% of cases despite neuropathy being present in 45.2%. Recurrence occurred in 16.1% of cases.

Conclusions Squamous cell carcinoma in people with diabetes-related foot disease is rare but frequently misdiagnosed, resulting in prolonged lesion duration prior to diagnosis. Clinicians should maintain a high index of suspicion for malignancy in atypical or non-healing foot lesions, particularly those with unusual features or persistence despite treatment. Early biopsy is essential for timely diagnosis and optimising outcomes.