This is a deep, irregulary shaped ulcer on the mid-sole of the right foot. There is no cm scale in the photo, but it must be at least 5 cm in diameter. The ulcer looks relatively clean. The base of the ulcer comprises of red fleshy tissue. It is not possible to see bone or tendons.
In this case the most likely explanation is recurrence of squamous cell carcinoma (SCC). It would be helpful to get his pathology report from his operation 18 months ago to confirm that it was SCC and to see whether it was completely excised at the time.
The differential diagnoses includes a neuropathic ulcer (this is less likely as the ulcer does not correspond to the area of sole with maximal pressure, and he has no history of neuropathy) and infection (which in this geographical setting may include fungi and mycobacteria: but note there is little discharge, swelling or surrounding inflammation).
You would want to examine his ipsilateral inguinal and femoral lymph nodes to check for signs of metastasis and if they are palpable a fine needle aspirate (or lymph node biopsy) should be sent to pathology.
A biopsy of the base of the ulcer for pathology would confirm or refute the diagnosis of recurrence of SCC.
A surgical opinion as to whether this is operable should be sought.
Further info
- Squamous cell carcinoma (Dermnet NZ)
A 42 year old man attends the dermatology clinic in Queen Elizabeth Central Hospital, Blantyre in 2012 with an ulcer on the sole of his right foot. He says that it has been present since 2004 but that he underwent surgery 1 and a half years ago. He was told it was a squamous cell carcinoma. It initially healed, but since then the skin has broken down and the ulcer is enlarging in size. He went back to see the surgeons and they have sent him on to dermatology to get dressings.