Figure 1 The patient’s clinical imaging data, along with the results of radiograph and MRI examinations and the histological analysis report. (A) A 48-year-old man with 2-year history of bilateral digital involvement (D2–D5 left, D2–D4 right) showing: erosions and ulcerations, hyperkeratotic squamous lesions, pyogenic granuloma-like changes, and nail dystrophy, along with a friable pink nodule on the right third finger exhibiting surface hemorrhage and necrotic foci. (B) Radiographs of the hand bilaterally showed destruction of the bone tissue of the fingers and no signs of osteomyelitis. (C) Contrast-enhanced MRI revealing a high-signal-intensity lesion in the right middle finger, with osteolytic destruction at the terminal aspects of the left index and middle fingers. (D) This case demonstrates a sarcomatoid squamous cell carcinoma of the skin, characterized by a deeply invasive spindle cell proliferation. At higher magnification, spindle-shaped neoplastic cells can be seen infiltrating between collagen fibers, as visualized on hematoxylin and eosin staining magnification ×100. (E) 18F-2-fluoro-2-deoxy-D-glucose positron-emission tomography. PET imaging demonstrated intense radiotracer uptake in the lesion of the right finger, suggesting high metabolic activity. No signs of tumor metastasis were observed. (F) The patient underwent 4 sessions of topical 5-aminolevulinic acid–mediated photodynamic therapy at 2-week intervals. Following an incubation period of 3–6 hours, the lesions were irradiated with red light (630–635 nm) at an energy density of 100 J/cm2 (range: 37–150 J/cm2) and a light intensity of 50–200 mW/cm2. (G) Follow-up photos taken 3 months after treatment completion. The lesion on the finger that had undergone excision showed local recurrence. (H) The distribution of squamous cell carcinoma and sarcomatoid carcinoma in the nail area.