Squamous Cell Carcinoma of the Thumb: Misdiagnosis and Consequences.

: Cutaneous squamous cell carcinoma (SCC) is the most common primary malignant tumor of the hand, and its aggressive nature can lead to significant morbidity, particularly when affecting critical structures like the thumb. SCC in this location may arise in the periungual area or the pulp and frequently presents with non-specific symptoms such as swelling, nail deformity, or discharge, features that closely mimic common benign conditions. : A retrospective study analyzed patients with neglected or misdiagnosed SCC of the thumb treated at the Hand and Microsurgery Unit of the Jewish Hospital, Rome, between 2015 and 2025. Patient demographics, duration from symptom onset to diagnosis, initial misdiagnoses, and imaging findings (X-rays, MRI, CT scans, lymph node sonography) were reviewed. Surgical interventions, histopathological grading, and postoperative management were documented, with long-term follow-up focusing on disease progression and patient survival. : Sixteen patients were included in the study. The mean age at surgery was 73.6 years (range: 55-93 years), with a mean delay of 8.2 months from symptom onset to diagnosis in 87.5% of cases. Initial misdiagnoses included verruca vulgaris, onychomycosis, paronychia, and osteomyelitis. Imaging consistently revealed soft tissue involvement, bony invasion, and occasional metastasis. Surgical approaches ranged from wide resection to amputation, with thumb reconstruction in selected cases and hand amputation in severe presentations. Long-term follow-up (mean 4.6 years) showed high morbidity, a reduction in hand function and QoL, and a 50% mortality rate, with two cases due to metastatic disease (12.5%). : Thumb SCC presents diagnostic and therapeutic challenges, exacerbated by late diagnosis and initial misdiagnoses. Multidisciplinary management involving early recognition, comprehensive imaging, appropriate surgical interventions, and vigilant follow-up is crucial for optimizing outcomes.