Primary cutaneous sarcomatoid carcinoma, also known as spindle cell carcinoma, is an exceedingly rare malignancy accounting for only 1% of squamous cell carcinomas (SCC) (Wernheden et al, 2022). It is a highly aggressive variant characterised by biphasic epithelial and mesenchymal components of uncertain pathogenesis and prognosis (Lee, 2020). Bowen’s disease is a rare, slow-growing skin disorder that presents as a scaly, red cutaneous patch.
Here, we report a case of sarcomatoid squamous cell carcinoma with overlying Bowen’s disease presenting as a non-healing traumatic ulcer of toe in a patient with type 2 diabetes.
Case presentation
A 75-year-old man with type 2 diabetes presented to community podiatry in July 2021 with a year-long history of a non-healing ulcer to his left third toe. He reported having dropped a chair on it and it had failed to heal since then.
He was initially treated with antibiotics and simple dressings as an outpatient. Serial clinical photographs were taken over this period (Figure 1). The first X-ray identifying loss of bone was taken in August 2021 and reported as showing bony destruction of terminal phalanx and middle phalanx of left third toe. He was seen every 2 weeks by podiatry to monitor progress. Serial X-rays were performed (Figure 2). He had a 6-week course of antibiotics to treat the suspected osteomyelitis.
He was seen in the diabetic foot multidisciplinary clinic on August 6, 2021 and the plan was to change footwear to relieve recurrent trauma and facilitate a trial of healing.
He was discussed again at a virtual meeting on October 28, 2021, and the decision was for phalangeal amputation of toe due to chronic hypergranulation and increasing pain from the toe.
A repeat X-ray in November, prior to surgery, showed further erosive changes of the medial aspect of the head of the proximal phalanx.
On December 16, he attended the day-case unit for phalangeal amputation. On closer inspection pre-operatively the wound looked less like over-granulation and more like a melanoma. The surgery was performed as planned (Figure 3).
Deep tissue was sent for histology and microbiology. Microbiology samples grew Proteus mirabilis, Staphylococcus aureus and Pseudomonas aeruginosa. Skin margins demonstrated sarcomatoid squamous cell carcinoma, with overlying Bowen’s disease (Figure 4 and Box 1). An aggressive and invasive skin cancer was diagnosed.
Following the primary histology result from the biopsy taken during amputation the patient was referred to dermatology on a 2-week referral pathway.
Melanoma multidisciplinary meeting staged the lesion as T4N0M0 and it was deemed “a very high-risk SCC”.
He was booked for a staging CT of the head, thorax, abdomen and pelvis to look for secondary spread, of which there was none.
He was reviewed in the dermatology follow up clinic on June 16, 2022. The wound had healed well and there was no ongoing evidence of SCC, Bowen’s, lymphadenopathy or concerning skin lesions elsewhere. He will be reviewed quarterly going forward.
Conclusion
A 75-year-old man underwent a phalangeal amputation of his toe for a diabetic foot ulcer which appeared unusual at the time of surgery. Sarcomatoid squamous cell carcinoma with overlying Bowen’s disease was the final diagnosis.
No metastatic spread found on CT. The patient continues on the high-risk follow-up schedule under dermatology.
Recommendations
Although it is more common that foot lesions in this cohort of patients are related to the complications of diabetes and microvascular disease, malignancy should not be overlooked. Histopathology is an important adjunct when treating diabetes-related foot lesions, especially if the clinical presentation is unusual. A low threshold for sending samples may avoid missing such conditions.
