Review of diagnostic methods and results for HIV‐associated disseminated histoplasmosis: Pathologists are not sufficiently involved

Abstract

Histoplasma capsulatum (H. capsulatum) is the causative agent of disseminated histoplasmosis, a major but neglected Acquired Immune Deficiency Syndrome (AIDS)-defining infection and cause of death in Latin America [1-3]. In tissues, H. capsulatum presents as small spherical or ovoid yeasts measuring 2-6 μm [4]. After inhalation, it makes a dimorphic transition from must-leaven to yeast to enter host histiocytes/macrophages and survive intracellularly. It can, thus, proliferate during active infection, or persist during asymptomatic infections and then reactivate [5].

The Current and Future States of Diagnostic Tests for Histoplasmosis with a Focus on People with HIV and Disseminated Histoplasmosis

“…Thus, it is likely that the true diagnostic yield of culture depends on the case definition, including which tests were available in the center to make up the underlying cases. Lastly, in a study of 349 PWH in French Guiana with disseminated histoplasmosis, 214 had at least one culture taken [ 37 ]. Liver biopsy yielded 86.9% sensitivity (53/61), lymph node 79.6% (43/54), bone marrow 77.6% (156/201), and lower digestive tract samples 74% (40/54) [ 37 ].…”

“…Lastly, in a study of 349 PWH in French Guiana with disseminated histoplasmosis, 214 had at least one culture taken [ 37 ]. Liver biopsy yielded 86.9% sensitivity (53/61), lymph node 79.6% (43/54), bone marrow 77.6% (156/201), and lower digestive tract samples 74% (40/54) [ 37 ]. Cultures of skin lesions are usually positive, but this represents a late diagnosis.…”

“…One study including 36 patients with advanced HIV reported a diagnostic sensitivity of 88 percent when blood culture and direct microscopy of peripheral blood smears were used concomitantly [ 38 ]. In French Guiana, among PWH, only 32 of 214 (14.9%) bone marrow specimens were sent for cytopathology, and lower numbers were sent for BAL and CSF specimens [ 37 ]. Cytopathology sensitivity was 34.4% (11/32) for bone marrow, 50% (5/10) for BAL, and 0% (0/5) for CSF [ 37 ].…”

“…In French Guiana, among PWH, only 32 of 214 (14.9%) bone marrow specimens were sent for cytopathology, and lower numbers were sent for BAL and CSF specimens [ 37 ]. Cytopathology sensitivity was 34.4% (11/32) for bone marrow, 50% (5/10) for BAL, and 0% (0/5) for CSF [ 37 ]. Pathology utilization was higher in general: 72.9% (43/59) for the lower digestive tract, 66.1% (39/63) for the lymph node, and 50.7% (38/75) for the liver [ 37 ].…”

“…Cytopathology sensitivity was 34.4% (11/32) for bone marrow, 50% (5/10) for BAL, and 0% (0/5) for CSF [ 37 ]. Pathology utilization was higher in general: 72.9% (43/59) for the lower digestive tract, 66.1% (39/63) for the lymph node, and 50.7% (38/75) for the liver [ 37 ]. Direct examination (rapid examination by mycologists shortly after they are obtained, as opposed to standard pathology staining) was utilized frequently, particularly for bone marrow and BAL (both > 97% of samples).…”