Review of the central nervous system cytopathology in human immunodeficiency virus infection

Abstract

The human immunodeficiency virus (HIV) is a neurotropic retrovirus capable of producing a wide spectrum of central nervous system changes. Nearly 40% of HIV-infected patients demonstrate neuropathy ranging from dementia to the opportunistic infections and neoplasia seen in the acquired immunodeficiency syndrome (AIDS). Dramatic increases in the numbers of AIDS cases have allowed for the cytotechnologist and cytopathologist to become acquainted with the various pathologic manifestations of HIV infection. In this review, we are reporting the HIV-related diseases in the central nervous system and the role of diagnostic cytology.

Atypical Cytomorphologic Appearance of <i>Cryptococcus neoformans</i>

“…8,[24][25][26] In fact, there exists some disagreement over whether C neoformans can form actual pseudohyphae or only chains of budding yeasts "resembling" pseudohyphae. 4,16,27 Nevertheless, despite this apparent disagreement, absence of pseudohyphae has been used as a point of differential diagnosis with a Candida-type species.…”

“…4,16,27 Nevertheless, despite this apparent disagreement, absence of pseudohyphae has been used as a point of differential diagnosis with a Candida-type species. 8,[24][25][26] In a recent review of pulmonary cryptococcal infection in the acquired immunodeficiency syndrome, the authors stated that the "distinction between the small [poorly encapsulated] forms of Cryptococcus and Candida species, including Torulopsis glabrata, can be made by the presence in Cryptococcus of capsules, round blastoconidia, narrowbased budding, and the lack of pseudohyphae [italics added]." 8 In the cases we describe above, C neoformans formation of chains of budding yeasts, actual pseudohyphae and germ tube-like structures was identified.…”

“…4,16 The appearance of C neoformans as budding yeast cells and the absence of pseudohyphae have been used as a point of differential diagnosis from a Candida-type species in several recent reviews that discuss the cytopathology of cryptococcal disease in HIV infection. 8,[24][25][26] However, other reports describe the identification of variant forms of C neoformans having pseudohyphae and germ tube-like structures in the CSF. 2,11 In addition, several references noted the existence of rare forms of C neoformans that produce chains of budding yeasts, 4,16 pseudohyphae, 4,27 germ tubes, 4 germ tube-like extensions 12 and true hyphae.…”

“…Narrow-based budding and a thick, mucoid capsule are characteristic. 11,[24][25][26] Smaller (2-5 µm), poorly encapsulated forms of C neoformans have also been reported. 3,7,8 Identification of the organism is aided by special stains, such as mucicarmine, Fontana-Masson and Gomorimethenamine-silver (GMS).…”

“…9 The diagnosis of cryptococcal infection of the CNS is usually made by cytologic examination of CSF 11,17,25 ; cytology has also proven useful in the diagnosis of pulmonary cryptococcal infection. 8,24 Surgical biopsy has also been used for the diagnosis of pulmonary cryptococcal infection, 8 including pleural infection, 10 as well as disseminated disease.…”