This solitary, very pruritic, annular lesion suggests dermatophytosis. KOH preparation verified the presence of Tinea faciei. This infection is usually associated with contact with a new kitten or puppy.
This clustered grouping of small, shallow erosions surmounting a slightly indurated plaque is characteristic for “cold sores.” Because no vesicles were present and the lesions appeared to be crusting over, the patient was advised to apply an OTC cream (docosanol 10%) per package insert instructions.
These small, pruritic papules appeared in the morning, which strongly suggests the bite of a nocturnal feeding arthropod. Insect bites arranged in clusters of 3 is typical for, but not diagnostic of, bedbug infestation.
These oval, dyschromic macules surrounded by a palpable scale-like border are pathognomonic of disseminated superficial actinic porokeratosis, a disorder seen usually in those who have had considerable lifelong exposure to sunlight.
Prominent, pigmented polyangular scales on the extensor surfaces of the arms, legs, and trunk suggested recessive X-linked ichthyosis. DNA analysis demonstrated an abnormal steroid sulfatase gene, which confirmed the diagnosis.
Eccentric darker pigmentation in this small asymptomatic lesion strongly suggests malignant melanoma. This patient had a history of non-melanoma skin cancer, but was unaware of the questionable growth.
While it might be tempting to dismiss this as a picker’s nodule, lesion’s thickness suggested the need for a biopsy, which revealed that the lesion was an infiltrative, invasive basal cell carcinoma. The lesson? Never hesitate to biopsy when the slightest uncertainty exists as to the correct diagnosis.