DOI: 10.12890/2025_005711
A silent invader: asymptomatic Rhodococcus infection unmasked in a patient with ectopic ACTH-dependent Cushing’s syndrome
Authors
shahzeb.saeed@vandaliahealth.org
Keywords
Rhodococcus equi, Cushing’s syndrome, ectopic ACTH secretion, opportunistic infection and immunosuppressionAbstract
Introduction: Rhodococcus species, particularly Rhodococcus equi, are rare opportunistic pathogens that typically affect immunocompromised individuals. These infections usually present with respiratory or systemic symptoms and are often linked to environmental exposure. Asymptomatic Rhodococcus infections are exceedingly rare and pose unique diagnostic and therapeutic challenges.
Case description: We report the case of a 29-year-old male who presented with new-onset diabetes mellitus, resistant hypertension and significant weight gain. Physical examination revealed features consistent with Cushing’s syndrome. Biochemical evaluation confirmed ACTH-dependent hypercortisolism with an elevated plasma ACTH level, and a lack of suppression on high-dose dexamethasone testing; imaging identified a suspicious pulmonary nodule. Bronchoscopic biopsy revealed no malignancy, however cultures grew Rhodococcus species. The patient denied any respiratory symptoms or environmental exposure. Initial antibiotic therapy with ciprofloxacin and rifampin was started. Follow-up imaging showed rapid enlargement of the pulmonary mass, prompting surgical resection. Histopathology revealed malakoplakia, and repeat cultures again yielded Rhodococcus spp. Antibiotics were adjusted to azithromycin and rifampin, and the patient was started on ketoconazole to manage hypercortisolism.
Conclusion: This case highlights the importance of considering opportunistic infections such as Rhodococcus spp. in immunocompromised patients, even in the absence of symptoms. It underscores the diagnostic value of investigating incidental findings in such populations and illustrates the need for prompt, multidisciplinary management to prevent disease progression.
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