Mark Crislip, MD


June 29, 2011

Differential Diagnosis

Ulcerative skin diseases are always a challenge, especially in a traveler, and often the only way to make the diagnosis is biopsy for pathology and cultures for unusual organisms. Several rules exist for typical bacterial (S aureus and S pyogenes) skin infections. These infections are never, ever chronic, bilateral, or ulcerative and patients always have a fever, a leukocytosis, or both.

Paracoccidioidomycosis,[1] also known as "Brazilian blastomycosis," is found throughout Central and predominately South America and can cause chronic skin lesions but usually as part of disseminated disease. It is a soil organism, and the mode of entry is inhalational with subsequent spread to the skin. These "skin lesions can be extremely polymorphic but often appear as warty, hyperkeratotic plaques or ulcerative, crusted lesions. They are commonly found near the mouth, anus, or genitalia." Cases of primary skin diseases after traumatic inoculation have been reported.[2]

Mycobacterium bovis, part of the M tuberculosis complex, is found throughout cattle south of the border. The infection presents like M tuberculosis. As a cow milker, this patientis at risk, although skin lesions from direct inoculation are rarely reported. M bovis is a common cause (6.7%) of TB in immigrants in San Diego county,[3] and a hint that the organism could be M bovis is pyrazinamide resistance.[4]

Sporotrichosis, due to Sporothrix schenckii, is often associated with cutaneous injury, classically from a rose thorn, although it is found on all plants and decaying organic material. Ulcers are a less common manifestation. The infection typically causes a nodular lymphangitis[5] but can cause ulcers that mimic pyoderma gangrenosum.[6]

Treponema pallidum pertenue, the cause of yaws, is a cutaneous cousin of syphilis that is endemic in South America. Spread by direct contact, the lesions tend to be large, flat, and warty in appearance. When and where this organism originated is still in doubt, but we know that "based on comparisons with other bacteria, we concluded that treponematoses did not emerge before our own species originated and that syphilis did not start affecting mankind only from 1492 onwards. Instead, it seems to have emerged in the time span between 16,500 and 5000 years ago. Where syphilis emerged, however, remains unsolved."[7]

(On a personal note, during my childhood, the popular burger joint in my neighborhood of northeast Portland was called "Yaws." I now wonder what was in the meat.)

Meleney synergistic gangrene is caused by S aureus and Group A Streptococcus and occurs in surgical wounds and after trauma. In this case, no gangrene was present, and the bacteria were colonizers of the wound rather than pathogens.

Diagnosis and Treatment

A biopsy revealed Leishmania, and cultures at the Centers for Disease Control and Prevention (CDC) grew L braziliensis. Both L mexicana and L braziliensis are common in Central America and are a common cause of local and disseminated mucocutaneous diseases. In discussing the results with the patient, he remembered receiving numerous sandfly bites, the vector of the parasite. The CDC will send the special media for proper culture and identification and are extremely helpful in deciding on treatment, the therapeutic options being pentavalent antimony and ketoconazole. This patient received a course of sodium stibogluconate without problems and the ulcers melted away.


Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as: