A 55-year old man presented with a two-day history of headache, fever and generalized weakness. He had received a cadaveric kidney transplant 5 years earlier. His medications included 5 mg oftacrolimus twice a day and 10 mg of prednisone daily. On neurologic examination, he was confused and incoherent. Cranial nerves were normal, but he had a hazy left retina. Magnetic resonance imaging of the brain with the administration of gadolinium showed multiple enhancing lesion in both cerebral hemispheres. Patient had subretinal abscess, the aspirate was stained, the findings are liekly to be –

**Core Concept**
The patient's presentation with fever, headache, and generalized weakness, along with a history of organ transplantation and immunosuppressive therapy, suggests an opportunistic infection. The presence of multiple enhancing lesions in the brain and a subretinal abscess indicates a systemic fungal infection, specifically a type of toxoplasmosis or a fungal pathogen such as Aspergillus.

**Why the Correct Answer is Right**
The patient's immunosuppressed state due to tacrolimus and prednisone makes him susceptible to opportunistic infections. The presence of multiple enhancing lesions in the brain and a subretinal abscess suggests a disseminated fungal infection. The aspirate from the subretinal abscess is likely to show fungal elements, such as hyphae or spores, which are diagnostic of an Aspergillus infection. Aspergillus is a common opportunistic pathogen in immunocompromised patients, and its infection can manifest in the brain and eyes.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because toxoplasmosis typically presents with a single enhancing lesion in the brain, usually in the posterior fossa or basal ganglia, and is associated with a lymphocytic response rather than a fungal infection.

**Option B:** This option is incorrect because Cryptococcus neoformans typically presents with meningitis or focal brain lesions, but it is not commonly associated with subretinal abscesses.

**Option C:** This option is incorrect because Histoplasma capsulatum typically presents with pulmonary symptoms and is not commonly associated with disseminated fungal infections in immunocompromised patients.

**Option D:** This option is incorrect because it is not a specific fungal pathogen and does not accurately describe the presentation or diagnostic findings of the patient.

**Clinical Pearl / High-Yield Fact**
In immunocompromised patients, a subretinal abscess is highly suggestive of an opportunistic fungal infection, such as Aspergillus, and requires prompt diagnosis and treatment to prevent further complications.

**Correct Answer:** D. The aspirate from the subretinal abscess is likely to show fungal elements, such as hyphae or spores, which are diagnostic of an Aspergillus infection.

✓ Correct Answer: A. Weakly positive acid fast bacilli