Sporotrichoid Lymphocutaneous Infections: Etiology, Diagnosis and Therapy - American Family Physician

www.aafp.org/afp VOLUME 63, NUMBER 2 / JANUARY 15, 2001 misdiagnosis and delay in the appropriate antimicrobial therapy. Familiarity with the characteristics of nodular lymphangitis allows the family physician to narrow the microbiologic differential diagnosis, obtain appropriate laboratory studies and initiate directed antimicrobial therapy. If complicating factors exist (such as infection in immunocompromised patients, pregnant women, or children), referral to an appropriate subspecialist may be necessary. Although the list of microorganisms is diverse, when considered in the context of exposure history, the differential diagnosis is, fortunately, limited (Table 1). The most common causes of nodular lymphangitis in the United States are S. schenckii, Nocardia brasiliensis, Mycobacterium marinum and Leishmania brasiliensis. Microbiologic diagnosis can usually be made when appropriate histologic stains and cultures of biopsied tissues are obtained. The clinical microbiology laboratory should be notified in advance so that optimal culture techniques can be performed. Because of the diversity of microorganisms and the lack of official reporting of cases, it is impossible to establish the true incidence of nodular lymphangitis. Rates of infection will vary substantially as a function of exposureprone activities, geographic location, travel history, occupation and hobbies. Practice experience and the lack of large case series S porotrichoid lymphocutaneous infection is a syndrome characterized by the development of superficial cutaneous lesions that progress along dermal and subcutaneous lymphatics. It is usually preceded by a welldefined episode of cutaneous inoculation or trauma (historical information that can be a helpful clue to the diagnosis). The classic pattern is described as “sporotrichoid” after the infection caused by the dimorphic fungus Sporothrix schenckii. However, the microbiologic differential diagnosis of this syndrome includes a variety of common and uncommon microorganisms. The syndrome is also known as nodular lymphangitis, a term that will be used in this article because it more accurately reflects the diverse microbiology and anatomic pathology of the condition. The infection is frequently confused with the more common forms of cellulitis and lymphangitis, typically caused by staphylococci and streptococci. Secondary infections by these common microbes can obscure the underlying cause, resulting in Sporotrichoid lymphocutaneous infection is an uncommon syndrome that is often misdiagnosed and improperly treated. Of the several hundred cases seen each year in the United States, the majority are caused by Sporothrix schenckii, Nocardia brasiliensis, Mycobacterium marinum or Leishmania brasiliensis. The “sporotrichoid” disease begins at a site of distal inoculation and leads to the development of nodular lymphangitis. Systemic symptoms are characteristically absent. By recognizing the distinct pattern of nodular lymphangitis and focusing on the diverse but limited etiologies, the physician can obtain the appropriate histologic and microbiologic studies and start targeted antimicrobial therapy. Therapy is generally continued for two to three months after the resolution of cutaneous disease. (Am Fam Physician 2001;63:326-32.)