A 30-year-old man presents with flat-topped papules that have appeared gradually on the flexor surfaces of his wrists. White streaks and patches are also found on the buccal mucosa of the patient’s mouth. Histologically, the lesions showed hyperkeratosis, thickening of the stratum granulosum, and a bandlike infiltrate of lymphocytes and macrophages in the upper dermis, disrupting the basal layer of the epidermis. Lymphocytes were mostly of the CD4+ immunophenotype. Which of the following is the appropriate diagnosis?
Correct answer : d
Lichen planus is a hypersensitivity reaction with lymphocytic infiltrates at the dermal-epidermal junction.
The disease is apparently initiated by epidermal injury.
This injury causes some epidermal cells to be treated as “foreign.” The antigens of such cells are processed by Langerhans cells.
The processed antigen induces local macrophage activation and lymphocytic proliferation. Macrophages and T lymphocytes disrupt the stratum basalis resulting in reactive epidermal proliferation (hyperkeratosis).
The skin displays multiple, flat-topped, violaceous, polygonal papules. The site of pathologic injury is at the dermal- epidermal junction, where there is a striking infiltrate of lymphocytes, many of which surround apoptotic keratinocytes.
These histologic features are not observed in the other choices.