Differential Diagnosis
- Single most likely diagnosis
- E) Sporotrichosis: This diagnosis is the most likely due to the patient's occupation as a nursery and garden shop owner, which increases her exposure to soil and plants. The presentation of a painless red papule with subcutaneous nodular lesions, especially after a skin injury (like a pimple), is consistent with sporotrichosis, also known as "rose gardener's disease." The disease is caused by the fungus Sporothrix schenckii, commonly found in soil and on plants.
- Other Likely diagnoses
- D) Histoplasmosis: Although less likely than sporotrichosis given the clinical presentation, histoplasmosis is a consideration due to the patient's residence in the southeastern USA, an area where Histoplasma capsulatum is endemic. However, histoplasmosis typically presents with pulmonary symptoms, and cutaneous manifestations are less common.
- A) Blastomycosis: Blastomycosis, caused by Blastomyces dermatitidis, is another fungal infection endemic to parts of North America, including the southeastern USA. It can cause skin lesions, but these are usually accompanied by systemic symptoms, making it less likely given the patient's presentation.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- C) Coccidioidomycosis: Although the patient resides in the southeastern USA, which is not the primary endemic area for Coccidioides species (mainly found in the southwestern USA), travel or other exposures could still result in infection. Coccidioidomycosis can have severe consequences if not treated, especially in immunocompromised individuals, making it a "do not miss" diagnosis.
- B) Candidiasis: While candidiasis is more commonly associated with mucocutaneous infections, especially in immunocompromised patients, a severe and disseminated form could potentially present with skin lesions. Given the potential severity, it's essential not to miss this diagnosis, although it's less likely given the patient's healthy status and the specific presentation.
- Rare diagnoses
- Other rare fungal infections could potentially cause similar symptoms but are less likely given the patient's presentation and geographic location. These might include chromoblastomycosis, mycetoma, or phaeohyphomycosis, among others. Each of these has distinct features and would be considered based on specific additional clues in the history or examination findings.