Painful Vesicular Lesions on Plantar Surface with Secondary Bacterial Infection

Case at a Glance

A 30-year-old male presented with acute onset of painful vesicular lesions on the plantar surface of his foot, accompanied by black subcutaneous dots, localized swelling, and signs of secondary bacterial infection.

Patient's Story

The patient initially noticed what appeared to be blister-like lesions on the sole of his foot several days prior to presentation. He is physically active and maintains good health, with a BMI of approximately 25 kg/m². Initially dismissive of the lesions, he became concerned when they became increasingly painful and additional lesions appeared, including two small black subcutaneous dots. Family members encouraged him to seek medical attention due to the unusual appearance and progression.

Initial Assessment

Physical examination revealed multiple vesicular lesions on the plantar foot surface with associated erythema and localized induration. The lesions were tender to palpation and produced serous drainage. The patient reported constant pain even at rest, with significant exacerbation during weight-bearing activities. The affected area demonstrated firmness and swelling compared to the contralateral foot. Two small dark subcutaneous lesions were noted adjacent to the primary vesicles.

The Diagnostic Journey

Initial differential diagnosis included vesicular foot dermatitis, pustular psoriasis, and secondary bacterial infection. Given the unilateral presentation, acute onset, significant pain, and signs of local inflammation with drainage, bacterial superinfection was strongly suspected. The presence of subcutaneous dark spots raised additional concern for deeper tissue involvement.

Final Diagnosis

Subcutaneous bacterial infection with possible abscess formation, secondary to primary vesicular dermatitis.

Treatment Plan

Empirical antibiotic therapy was initiated to address the suspected bacterial infection. The patient was provided with wound care instructions and advised to minimize weight-bearing activities. Pain management strategies were discussed, including the use of soft padding for ambulation when necessary.

Outcome and Follow-up

The patient was scheduled for follow-up evaluation within 72 hours to assess treatment response and monitor for improvement in pain and local inflammatory signs. Close monitoring was planned to ensure adequate response to antibiotic therapy and to evaluate the need for further intervention if clinical improvement was not observed.