Multiple Keratotic Papules on the Left Sole of a 35-year-old Woman

CASE REPORT A 35-year-old female presented with multiple asymptomatic spiny protrusions on her left sole, which gradually accumulated for 2 years. Clinical examination revealed hundreds of asymmetrically distributed, minute, flesh-colored, keratotic papules on the patient's left sole (Fig. 1). On close-up inspection, the lesions, which measured 0.5 to 2 mm in height, were firmly attached. The papules appeared like crystals emerging from the skin (Fig. 2). The surrounding skin of the sole was normal. The patient's face, palm, and right sole also were not involved. Additionally, the patient did not exhibit any hair, teeth, or skeletal abnormalities. The patient reported that no family member had similar lesions. Arsenic exposure was not reported by the patient. A skin biopsy was taken from a papule on the left sole revealed compact parakeratotic vertical columns, under which the granular layer was decreased. There was no evidence of dyskeratosis or vacuolation degeneration in the epidermis (Fig. 3).