Advice with patient with unusal painful lesion/area

I saw this 37 year old patient today who presented with a red, painful swelling on the plantar surface of his right foot distal to the metatarsal head of 24 hours duration. I expected there to be an inter-digital fissure or wound which might have been a portal of entry for infection. However the skin was intact and I was baffled.

I saw this 37 year old patient today who presented with a red, painful swelling on the plantar surface of his right foot distal to the metatarsal head of 24 hours duration. I expected there to be an inter-digital fissure or wound which might have been a portal of entry for infection. However the skin was intact and I was baffled.

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Advice with patient with unusal painful lesion/area