Dermatology

Prepared by Richmond McCarty, DO, USAF Flight Surgeon, and Terri Nutt, MD, Chief of Dermatology, David Grant Medical Center, Travis AFB, Calif

A 37-year-old woman presented with a 1-week history of multiple erythematous, scaly papules on her scalp, trunk (Figure), upper extremities, and pelvic area. She stated that the lesions did not itch and were not painful. On further questioning, the patient admitted to taking some leftover penicillin 2 weeks earlier for a self-diagnosed "strep throat." The patient denied any recent travel outside the United States and reported minimal improvement with the use of over-the-counter hydrocortisone cream. She also denied any sexual contact outside her marriage for herself and her husband.

Figure

What's Your Diagnosis?

• Secondary syphilis
• Guttate psoriasis
• Drug reaction
• Pityriasis rosea

Quiz Answer

Guttate psoriasis—This condition is classically preceded by streptococcal pharyngitis or by an upper respiratory viral infection a week or two earlier. It is characterized by the sudden appearance of plaques and round, scaling papules on the trunk and extremities, sparing the soles of the feet and palms of the hands. These dropletlike lesions serve as a hallmark for the disease and usually exhibit some degree of central clearing. Guttate psoriasis usually occurs in children and young adults and resolves spontaneously within weeks to months after the initial eruption. It is estimated that 33% to 66% of patients with a history of guttate psoriasis will develop chronic plaque psoriasis.¹ Our patient had an elevated antistreptolysin-O titer, and her tissue biopsy confirmed the diagnosis of guttate psoriasis.² She was subsequently referred to a local dermatologist for ultraviolet B light therapy.

Secondary syphilis is characterized by mucocutaneous lesions, flulike symptoms, and adenopathy (which is usually painless). It manifests approximately 6 weeks after the primary chancre and can last between 2 and 10 weeks. It is generally associated with low or no fever during the initial onset, and the lesions tend to develop slowly, with little or no inflammation. Pain and itching are usually minimal, and various types of lesions often present simultaneously rather than as a single uniform eruption. In the majority of patients, lesions are typically found on the hands and feet and are distributed throughout the trunk. Our patient had no other systemic symptoms or associated lesions on the palms of her hands or the soles of her feet, and denied any unfaithfulness on her or her husband?s part. A Venereal Disease Research Laboratory test for syphilis was ordered, but the laboratory was unable to process the sample for an unknown reason.

Drug reactions can occur within hours after ingestion, or up to several weeks after the initial exposure. The reactions tend to be pruritic and present with a diffuse and symmetrical maculopapular rash and with generalized urticaria. These eruptions are very similar to that of a viral exanthema; it can be hard to differentiate between the two. Our patient did not exhibit fever or urticaria, and her lesions presented gradually, whereas drug reactions tend to present with a moresudden onset.

Pityriasis rosea is a benign, asymptomatic, self-limited skin eruption of unknown etiology. It is often preceded by a history of acute infection and presents with multiple oval lesions that have a thin collarette scale and can be mildly pruritic. The long axis of the lesions tends to be oriented with the skin lines, which can give a characteristic "Christmas tree" distribution. Only a small percentage of patients present with a herald patch, which our patient did not have. This condition was high on the differential diagnosis list for our patient; the tissue biopsy helped rule it out.

References

1. Scatena L. What triggered this sudden eruption? Am J Med. 2005;118:362-363.
2. Gudjonsson JE, Thorarinsson AM, Sigurgeirsson B, et al. Streptococcal throat infections and exacerbation of chronic plaque psoriasis: a prospective study. Br J Dermatol. 2003;149:530-534.

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