Heartland Virus and Hemophagocytic Lymphohistiocytosis in Immunocompromised Patient, Missouri, USA.

Heartland virus is a suspected tickborne pathogen in the United States. We describe a case of hemophagocytic lymphohistiocytosis, then death, in an immunosuppressed elderly man in Missouri, USA, who was infected with Heartland virus.

Brown-Pigmented Mycobacterium mageritense as a Cause of Prosthetic Valve Endocarditis and Bloodstream Infection.

Mycobacterium spp. are a rare cause of endocarditis. Herein, we describe a case of Mycobacterium mageritense prosthetic valve endocarditis. This organism produced an unusual brown pigment on solid media. Cultures of valve tissue for acid-fast bacilli might be considered in some cases of apparently culture-negative prosthetic valve endocarditis.

Hematogenous vertebral osteomyelitis.

Hematogenous vertebral osteomyelitis is an increasingly important consideration in the differential diagnosis of patients presenting with back pain even in the absence of fever. The incidence of this disease is increasing and physicians must maintain a high index of suspicion to make a prompt diagnosis. In patients with progressive neurologic deficits, urgent diagnosis is imperative, as the window for necessary surgical intervention is narrow. Magnetic resonance imaging is the preferred radiologic modality because of its sensitivity. Bone biopsy is the gold standard for diagnosis and is usually performed percutaneously using CT-guidance. Antimicrobial therapy of at least six weeks in duration is recommended and should be tailored to pathogens recovered from bone biopsy culture. With improved diagnostic techniques and prompt management, adverse outcomes associated with a delay in diagnosis can be avoided.

Pseudotumor of the tracheal-laryngeal junction with unusual morphologic features caused by Rhodococcus equi infection.

Infectious pseudotumors are unusual proliferations of histiocytes in response to certain microbial organisms. Occasionally this process may involve large airways, producing a mass lesion that may cause respiratory obstruction. Infectious pseudotumors can be confused with malignancy in their radiologic appearance and clinical presentation. We present a case of an aggressive endotracheal pseudotumor associated with Rhodococcus equi infection in a patient with advanced HIV disease. Microscopically, the lesion was composed of sheets of epithelioid histiocytes with large, strongly eosinophilic intra-cytoplasmic granules and features of malakoplakia. In this report, we review the literature of these unusual lesions and compare them to cases of conventional malakoplakia involving the large airways. We also explore the pathogenetic mechanisms that may contribute to the distinctive histologic appearance of Rhodococcus-associated pseudotumors.