Nummular Eczema and Fixed Drug Eruption

Transcription

1 May 01, 2006 For the past few weeks, pruritic patches have been erupting on a 38-year-old man s extremities. He recalls that similar lesions occurred during the last 2 winters. The patient has a history of seasonal allergies; he owns a cat and 2 dogs. Case 1: For the past few weeks, pruritic patches have been erupting on a 38-year-old man's extremities. He recalls that similar lesions occurred during the last 2 winters. The patient has a history of seasonal allergies; he owns a cat and 2 dogs. Your clinical impression is... A. Nummular eczema. B. Ringworm. C. Psoriasis. E. Pityriasis rosea. What action do you take? F. Perform a skin biopsy. G. Perform a potassium hydroxide evaluation. H. Recommend the use of mild soaps and moisturizers. I. Recommend that a veterinarian examine the pets. J. Prescribe a corticosteroid cream. Case 2: A 39-year-old woman, who is being treated for a urinary tract infection, is concerned about a red, slightly tender spot on her forearm. She recalls having had a similar lesion several years earlier. The patient has 2 cats. What do you suspect? A. Superficial basal cell carcinoma. B. Nummular eczema. C. Fixed drug eruption. D. Tinea corporis. E. Contact dermatitis. What course of action do you pursue? F. Ask the patient about the medications she is taking. G. Perform a skin biopsy. H. Question the patient about the previous similar eruption. I. Prescribe an antifungal cream. Page 1 of 5

2 J. Switch to another antibiotic for the urinary tract infection. Case 1: Multiple, pruritic, coinshaped lesions that erupt during cold weather--particularly in persons with atopy--strongly suggest nummular eczema, A. Typically, only 1 or 2 inflamed lesions occur when a pet is the source of ringworm, which can be ruled out by a potassium hydroxide evaluation, G. The lesions of contact dermatitis usually are less well-defined and generally occur on exposed areas; because it was winter, this patient's arms and legs had been covered. Pityriasis rosea arises on the trunk, and psoriasis affects the knees and elbows, which were clear in this patient. The seasonal recurrence of multiple lesions is not a feature of skin cancer; thus, a biopsy was not warranted. The patient was advised to use a mild soap and to apply moisturizer assiduously, H, to his sensitive skin. The eczema responded quickly to a topical corticosteroid, J. Case 2: Further questioning revealed that the patient was taking a sulfa antibiotic, F, for the urinary tract infection. She also remembered that the previous eruption had occurred after she had been given a sulfa agent, H. This history supported the diagnosis of a fixed drug eruption, C a circular, erythematous lesion that recurs at the same location after rechallenge with the same drug. The original antibiotic was discontinued, and a nonsulfa agent was prescribed, J. If the eruption had not cleared, a biopsy to rule out skin cancer may have been appropriate. The coin shape of this lesion suggested nummular eczema, but its solitary appearance and the absence of pruritus ruled out that disease. Pruritus is characteristic of contact dermatitis and tinea corporis lesions, which are not transient or tender. Case 3: The parents of an 8-year-old boy seek evaluation of a red patch on their son's shoulder. The asymptomatic spot erupted 2 weeks earlier. The patient has seasonal allergies and frequently plays with his dog. What does this look like to you? A. Psoriasis. B. Tinea corporis. C. Impetigo. E. Erythema migrans. What is your initial approach? F. Perform a skin biopsy. G. Perform a patch test. H. Perform a potassium hydroxide evaluation. I. Perform a bacterial culture. Page 2 of 5

3 J. Recommend that a veterinarian examine the dog. Case 4: For a few months, a 47-year-old man has noted a persistent, asymptomatic patch on his upper arm. The patient has no significant medical problems, takes no medications, and has no history of seasonal allergies. He keeps a pet cat and enjoys gardening. Do you recognize this lesion? A. Nummular eczema. B. Basal cell carcinoma. C. Actinic keratosis. D. Pityriasis rosea. E. Tinea corporis. What do you do now? F. Prescribe an antifungal antibiotic. G. Perform a potassium hydroxide evaluation. H. Perform a complete laboratory workup. I. Perform a skin biopsy. J. Observe and follow up in 3 months. Case 3: A potassium hydroxide evaluation, H, confirmed tinea corporis, B, which responded to a topical antifungal. The family was advised to have their dog examined by a veterinarian, J, since the pet was the suspected source of the dermatophyte. Erythema migrans associated with Lyme disease was unlikely, since the patient had no prodromal symptoms and the lesion developed in winter, far beyond the tick bite transmission season. Because the single lesion was not pruritic and erupted on a site that was covered by clothing, patch tests for contact dermatitis were not warranted. The lesion demonstrated far less scale than is seen in psoriasis; the absence of tender, crusted vesicles ruled out impetigo. Case 4: A skin biopsy, I, confirmed the clinical suspicion of basal cell carcinoma, B. Because the patient worked shirtless every summer in his garden, actinic keratosis was a diagnostic consideration. The basal cell carcinoma was excised completely, and the patient was instructed to use sunscreen when exposure to the sun could not be avoided. This asymptomatic lesion was neither pruritic nor scaly, thus ruling out nummular eczema and pityriasis rosea, respectively. Fungal infections generally are scaly and often pruritic; although they Page 3 of 5

4 expand slowly, they do so more quickly than basal cell carcinoma. Case 5: A 41-year-old man has been bothered by an itchy rash on his hands for several weeks. The patient, a florist whose hands are frequently in water, has used the same moisturizer for years. What has caused this condition? A. Psoriasis. B. Tinea manus. C. Lupus erythematosus. E. Dyshidrotic eczema. How would you confirm your diagnosis? F. Examine the patient's nails. G. Perform patch tests. H. Obtain an antinuclear antibody titer. I. Perform a skin biopsy. J. Perform a potassium hydroxide evaluation. Case 6: A 14-month-old boy presented with a 1-week history of a spreading, red rash on his left hand. He frequently sucks on the hand. The child is otherwise healthy; there is no family history of seasonal allergies. What is your tentative diagnosis? A. Impetigo. B. Candidiasis. C. Irritant dermatitis secondary to maceration and moisture. D. Dermatophyte infection. E. Herpetic whitlow. How do you confirm your diagnosis? F. Perform a bacterial culture. G. Perform a fungal culture. H. Perform a viral culture. I. Perform a potassium hydroxide evaluation. J. Perform patch tests. Case 5: Patch tests, G, not only confirmed contact dermatitis, D, but determined the culprit was African violets. A topical corticosteroid hastened resolution of the outbreak. The patient now wears vinyl gloves when handling these plants. Examination of the nails, F, did not reveal nail pitting, which is a hallmark of psoriasis. Tinea manus features scaling, erythematous eruptions on the palms that often spare the dorsa of the hands; this dermatophyte infection can be ruled out by a potassium hydroxide evaluation. The rash of lupus Page 4 of 5

5 erythematosus usually involves the upper trunk and only the dorsa of the hands. Dyshidrotic eczema is a chronic condition that features deep-seated vesicular eruptions, primarily on the palms and the sides of the fingers. Case 6: A potassium hydroxide evaluation, I the least costly and most expedient of the diagnostic procedures confirmed candidiasis, B, and ruled out a dermatophyte infection, which would be unusual in an infant. If necessary, a bacterial culture could be done to eliminate impetigo, which may resemble a Candida infection. More severe redness and scaling is expected at the site of an irritant dermatitis secondary to maceration and moisture. The typical presentation of herpesvirus infection grouped vesicles on an erythematous base was not seen here. A topical antifungal agent cleared the candidiasis. To prevent the child from sucking on the treated hand, a single coat of the agent was applied after he fell asleep for the night. Source URL: Page 5 of 5