A 46-year-old man comes to the office due to skin lesions that developed on his left arm over the past few days. The lesions are not particularly painful. The patient has never had similar symptoms. He has had no fevers and otherwise feels fine. Past medical history is insignificant. The patient takes no medications and has no allergies. Temperature is 37.1 C (98.8 F). The lesions are shown in the image below. Following pathologic sampling, the lesions are determined to be fungal in etiology. Which of the following scenarios is most likely a component of this patient's history?

Question

A 46-year-old man comes to the office due to skin lesions that developed on his left arm over the past few days.  The lesions are not particularly painful.  The patient has never had similar symptoms.  He has had no fevers and otherwise feels fine.  Past medical history is insignificant.  The patient takes no medications and has no allergies.  Temperature is 37.1 C (98.8 F).  The lesions are shown in the image below.  Following pathologic sampling, the lesions are determined to be fungal in etiology.  Which of the following scenarios is most likely a component of this patient's history?

Quizplus · Accepted Answer

This patient has a fungal dermatologic infection. The subcutaneous nodules pictured are consistent with sporotrichosis, a subcutaneous mycosis caused by Sporothrix schenckii. Sporothrix is a dimorphic fungus found in the natural environment in the form of mold (hyphae). It resides on the bark of trees, shrubs, and garden plants and on plant debris in soil. It enters the body through breaks in the skin (often via thorn prick) and spreads along the lymphatics. Sporotrichosis is commonly seen in gardeners. The initial lesion - a reddish nodule that later ulcerates - appears at the site of the thorn prick or other skin injury. Biopsy of the lesion typically reveals a granuloma consisting of histiocytes, multinucleated giant cells, and neutrophils, surrounded by plasma cells. From the site of inoculation, the fungus spreads along the lymphatics, forming subcutaneous nodules and ulcers. The diagnosis of sporotrichosis is made by culturing the affected area and isolating S schenckii. Antifungal therapy (eg, itraconazole) is needed. (Choice A) Animal contact is associated with dermatophytoses caused by Microsporum species. Microsporum canis causes tinea capitis. Cat scratch disease (manifesting as a vesicle turning into a papule and accompanied by lymphadenopathy) is due to Bartonella, which is a gram-negative bacterium, not a fungus. (Choice B) Exposure to bats (eg, during cave exploration) or to bird droppings in the Ohio and Mississippi River Valley areas is associated with Histoplasma capsulatum infection, which typically causes lung disease resembling tuberculosis. (Choice C) The bacterial organisms Aeromonas and Vibrio vulnificus may cause cellulitis related to freshwater or seawater exposure. (Choice D) Immune system disease predisposes to systemic mycoses (eg, candidiasis, aspergillosis, mucormycosis). Sporotrichosis, in contrast, commonly affects immunocompetent individuals. Disseminated sporotrichosis is very rare. (Choice E) Recent antibiotic use is associated with superficial Candida disease, such as oral thrush or vulvovaginitis. Educational objective: Sporothrix schenckii is a dimorphic fungus that causes a subcutaneous mycosis. It is often transmitted by a thorn prick. The disease manifests with nodules that spread along lymphatics.

A 46-Year-Old Man Comes to the Office Due to Skin