A Woman with a Skin Ulcer

Posted by • February 12th, 2016

2-9-2016 9-19-51 AMUlceroglandular tularemia is one of several clinical presentations of Francisella tularensis infection. In patients with ulceroglandular tularemia, an ulcer develops at the site of inoculation and is followed by fever, systemic symptoms, and regional lymphadenopathy. Although tularemia can occur year-round, it predominantly occurs during the summer months. The diagnosis of tularemia is quite rare; in the United States, 200 cases per year are reported to the Centers for Disease Control and Prevention.

A 58-year-old woman presented during the summer with fever, neck swelling, and an ulcerated lesion on the forehead. Imaging of the neck showed enlarged, centrally hypodense lymph nodes with infiltration of the surrounding fat. Tests were performed, and a diagnosis was made. A new Case Record summarizes.

Clinical Pearl

• What is included in the differential diagnosis for a patient with an ulcerated skin lesion and lymphadenopathy?

Bubonic plague, caused by Yersinia pestis, is endemic in the southwestern United States. The incubation period for this pathogen is 2 to 8 days, and untreated infection leads to rapid death from septic shock. Patients with rickettsialpox, caused by Rickettsia akari, typically present with a poxlike lesion that contains a central eschar, as well as a characteristic papulovesicular rash on the trunk, arms, or legs that occurs within a week after symptom onset. In patients with cat scratch disease, caused by Bartonella henselae infection, the inoculation site (usually a bite or scratch by an infected cat) rarely has ulceration. The presentation of cat scratch disease is dominated by lymphadenopathy and fever. Primary cutaneous Mycobacterium tuberculosis infection is acquired through direct entry of the pathogen through the skin and causes an ulcerated skin lesion with lymphadenopathy that develops slowly, over 3 to 4 weeks. Given the association of Bacillus anthracis with bioterrorism, it is important to remain familiar with the clinical features of cutaneous anthrax and to at least consider the diagnosis in patients who present with an ulcerated skin lesion, possible eschar, and lymphadenopathy. There has been no reported bioterrorism activity involving anthrax in the United States since 2001. Outside of a bioterrorism event, the diagnosis of cutaneous anthrax is unlikely in the absence of a history of international travel or exposure to animal products from areas where the disease is endemic, such as Africa, Pakistan, and Iraq.

Clinical Pearl

• Tularemia is most common in what region of the United States?

Tularemia most commonly occurs in the south central United States. However, rabbits from the south central United States were imported to the island of Martha’s Vineyard for gaming in 1937. Since then, the 5 to 10 cases of tularemia that are reported each year in Massachusetts occur almost exclusively on Martha’s Vineyard, where tularemia in the rabbit and tick population is endemic.

Morning Report Questions

Q: How is tularemia diagnosed?

A: Because the associated microorganism is fastidious, special laboratory safety considerations are required because infection can occur after exposure to a low dose and through inhalation; therefore, most diagnoses are made serologically. The definitive serologic diagnosis of tularemia requires either that the specific antibody titer must increase to four times as high as the normal level over a period of at least 14 days or that a single positive result must have a titer higher than 1:80 in the absence of a known previous exposure. In cases of ulceroglandular tularemia in which the test for antibodies during the acute phase is nondiagnostic, a culture of the ulcer specimen can provide the most rapid diagnosis; however, this technique is not sensitive. Rapid inoculation of medium and extended incubation may increase the chances of recovering the microorganism in culture. Some public health and reference laboratories also offer polymerase-chain-reaction (PCR) testing for the rapid detection of F. tularensis DNA in clinical specimens, but such testing is not widely available, and the clinical sensitivity of PCR testing for the diagnosis of tularemia has not been well characterized.

Q: What is the recommended treatment for tularemia?

A: The treatment of choice for moderate-to-severe cases of tularemia is an antibiotic agent in the aminoglycoside class, whereas milder cases can be treated with oral agents, including fluoroquinolones (typically ciprofloxacin) or tetracyclines (typically doxycycline), often in combination. These recommendations are supported by a number of recent case series. Among the aminoglycosides, intramuscular streptomycin is preferred; intravenous gentamicin is considered to be an acceptable alternative if streptomycin is unavailable. Some instances of treatment failure with gentamicin have been reported, and rescue therapy with streptomycin has been successful. As patients with moderate-to-severe tularemia improve with the administration of an aminoglycoside, transition to oral therapy with either a fluoroquinolone or a tetracycline is common.

Figure 2. Clinical Photographs.

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