Review Question - QID 103818

This patient is presenting with a pruritic and vesicular rash suggesting a diagnosis of contact dermatitis. Pathology will show spongiosis (intercellular edema in the epidermis) in acute contact dermatitis.

Contact dermatitis is a type IV (delayed) hypersensitivity reaction, which occurs when a patient comes into contact with an allergen to which they have been previously sensitized. The antigenic substances penetrate the skin, are phagocytized by Langerhans cells, and are carried to lymph nodes where they are presented to T lymphocytes. On repeat exposures, a reaction can be expected to appear in 24-48 hours. Pathological findings in acute contact dermatitis include mild spongiosis, intraepidermal vesicles/bullae, and necrosis of keratinocytes. The treatment of contact dermatitis is topical steroids unless the face or a cosmetic region is affected or if there is substantial skin involvement (in which case oral steroids may be given).

Figure A shows the typical rash in a patient with a contact dermatitis with pruritic vesicles.

Incorrect Answers:
Answer 1: Acanthosis (diffuse epidermal hyperplasia) is typically seen in psoriasis and in acanthosis nigricans. It can also be seen in chronic contact dermatitis which also presents with hyperkeratosis, parakeratosis, and hypergranulosis.

Answer 2: Caseating granulomas are a classic finding in tuberculosis and certain infections.

Answer 3: Extraepidermal vesicles with keratinocytes are not associated with a contact dermatitis; however, intraepidermal vesicles with keratinocytes are characteristic of herpes virus infections.

Answer 4: Langerhans giant cells are often found in fungal infections, syphilis, sarcoidosis, leprosy, and tuberculosis.

Bullet Summary:
Spongiosis can be seen in a contact dermatitis.