A 52-year-old woman comes to the office due to worsening skin lesions on her right hand. The patient injured her hand while cleaning decaying vegetation from her rose garden 3 weeks ago. She washed the wound with soap and water and noticed a mildly itchy papule several days later. The lesion progressively enlarged, and 2 other similar papules appeared proximal to the original lesion. The patient has had no fever, chills, or severe pain. She has no previous medical conditions and takes no medications. The patient lives in the southeastern United States and has not traveled recently. Physical examination shows a 1-cm, nontender, red nodule on the dorsum of the right hand with 2 smaller papules in linear distribution proximal to it. Which of the following histopathologic findings is most likely present in this patient's skin lesions?
Sporotrichosis is caused by Sporothrix schenckii, a dimorphic fungus found in soil and plant matter that may be traumatically inoculated into the skin (eg, thorn prick) during outdoor activities (eg, gardening, landscaping). A mildly pruritic, erythematous, ulcerated papule often forms at the inoculation site (eg, hand, forearm) within weeks. As the organism spreads, additional lesions may develop along the draining lymphatic chain (ie, nodular lymphangitis).
Biopsy of the lesions reveals mixed inflammation, including granulomas and neutrophilic microabscesses in the dermis and subcutaneous tissue. Stains for fungal organisms may highlight rare, cigar-shaped yeast. The gold standard for definitive diagnosis is culture.
Sporotrichosis is typically limited to the skin and soft tissue, but disseminated infection may develop in immunocompromised individuals. Itraconazole is the preferred treatment for lymphocutaneous sporotrichosis.
(Choice A) Histologic features of actinomycosis include sulfur granules (aggregates of Actinomyces filaments) surrounded by a dense inflammatory infiltrate. Actinomycosis most commonly presents as a firm cervicofacial (eg, mandibular) mass with abscess and sinus tract formation after surgery (eg, tooth extraction) or trauma.
(Choice B) Cutaneous leishmaniasis is histologically characterized by granulomatous inflammation and intracellular amastigote organisms within macrophages. Although it may present with ulcerated papules and nodules, cutaneous leishmaniasis is most frequently seen in the Middle East and Central and South America; this patient lives in the southeastern United States and has not traveled recently.
(Choice D) Spongiosis (ie, epidermal intercellular edema) and superficial dermal perivascular inflammation are histologic features of acute eczematous dermatitis, such as allergic contact dermatitis (eg, poison ivy). Clinical manifestations typically include erythematous, pruritic papules and vesicles, rather than nodular lesions.
(Choice E) Prominent plasma cell infiltrates and obliterative endarteritis are characteristic of syphilitic lesions. Depending on the stage of infection, cutaneous syphilitic lesions may include painless ulcers (eg, chancre), gray-white plaques (eg, condylomata lata), a maculopapular rash, and gummas.
Educational objective:
Sporotrichosis typically presents as papulonodular lesions distributed along the lymphatics and is histologically characterized by granulomatous and neutrophilic inflammation. It is caused by the dimorphic fungus Sporothrix schenckii, which is often inoculated into the skin during outdoor activities such as gardening.