A 62 year old woman, who had type 2 diabetes of 15 years’ duration, developed community acquired pneumonia. Her sensorium was normal. Skin examination revealed bilateral tense painless bullae on her soles and toes (fig 1). She had peripheral sensory motor neuropathy. Bullae aspiration revealed clear fluid. Immunofluorescent studies and fluid cultures were negative. The bullae healed over two weeks.

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Figure 1

 Soles of patient showing tense bullae.

About 0.5% of diabetics develop diabetic bullae or bullosis diabeticorum, a distinct diabetic marker. The bullae occur more frequently in adult men with long standing diabetes and neuropathy. The pathogenesis of diabetic bullae is unclear. These painless bullae may be the first presentation of diabetes, appearing suddenly, commonly on lower limbs. They range in size from a few millimeters to several centimeters, have a non-inflamed base, and contain clear sterile fluid.

The differential diagnosis includes several bullous disorders; diagnosis is of exclusion. Healing is spontaneous in a few weeks but they may reoccur.