Which organism is identified by a bone marrow sample revealing small intracellular cells and showing a dimorphic growth phase?

The identification of an organism based on a bone marrow sample that reveals small intracellular cells and exhibits a dimorphic growth phase aligns with Histoplasma capsulatum. This fungus is known for its dimorphic nature, meaning it can exist in two different forms: as a mold in the environment and as a yeast when infecting a host.

Histoplasma capsulatum is particularly associated with histoplasmosis, which often leads to infection in individuals who are immunocompromised or have been exposed to contaminated soil, especially in areas where there is bat or bird droppings. Inside human tissues, particularly in macrophages, the yeast form of this organism is typically observed. The small intracellular cells found in bone marrow samples can indicate an active infection where the immune cells have attempted to engulf and contain the fungus.

In contrast, the other organisms listed, while they may also be dimorphic or have particular associations with human disease, do not primarily show the same intracellular characteristics in bone marrow samples. For instance, Sporothrix schenckii, which causes sporotrichosis, typically manifests in skin lesions, while Coccidioides immitis can cause coccidioidomycosis with a focus on lung involvement rather than exclusively in