Diagnosis of Infectious Diseases: a Cytopathologist’s Perspective

Abstract

SUMMARY This review explores the role of the cytopathology laboratory in the detection and presumptive identification of microorganisms. Sample procurement by exfoliation, abrasion, and aspiration techniques, as well as a variety of cytopreparatory and staining methods, is reviewed. Emphasis is placed on the utility of fine-needle aspiration as a rapid, safe, and cost-effective diagnositic procedure. The role of rapid interpretation and specimen triage is also discussed. Cytomorphologic features and staining characteristics are presented for a spectrum of microorganisms potentially encountered in the cytopathology laboratory. Pitfalls in diagnosis and the usefulness of special stains and ancillary techniques are also evaluated. The importance of communication, collaboration, and clinical correlation is stressed.

From the patient to the clinical mycology laboratory: how can we optimise microscopy and culture methods for mould identification?

“…Aspergillus spp. and the mucoraceous moulds stain fairly well with Papanicolaou or haematoxylin-eosin (H&E), but Grocott-Gomori methenamine silver (GMS) stain is considered by many to be the best stain to reveal fungal hyphae 38. Another suitable stain is periodic acid-Schiff (PAS) or the diastase modification (dPAS), which improves background staining by removing glycogen.…”

“…In cytology specimens, most fungi are identified and diagnosed by their morphological (hyphal or yeast structures, size, shape, budding, mode of branching) rather than staining characteristic 38. This approach, combined with clinical information, helps in the selection of the stain that will display and enhance the morphological characteristics and in the differential diagnosis.…”

More experiences with the Tzanck smear test: Cytologic findings in cutaneous granulomatous disorders

“…The number of skin diseases, lesion types and characteristic cytologic findings are shown in Table I. 1,2,[7][8][9][10][11][12][13] To reach the final diagnoses in study patients, the following laboratory examinations were performed: histopathologic examination in 69 (73.4%) patients, leishmania culture in 39 (41.5%) patients, leishmania and tuberculosis PCR in 37 (39.4%) patients, fungal culture in 5 (5.3%) patients, bacterial cultures in 5 (5.3%) patients, and potassium hydroxide examination in 2 (2.1%) patients. None of the patients in the cytologically-examined group had a granulomatous disorder that was not identified by Tzanck smear.…”

“…Noninfectious granulomatous reaction was due to granuloma annulare in 7 patients, sarcoidosis in 5 patients, foreign body granuloma in 4 patients, necrobiosis lipoidica in 2 patients, and juvenile xanthogranuloma in 2 patients (see Table I). 1,2,[7][8][9][10][11][12][13] Cytologic findings Infectious granulomatous diseases. The sensitivity and specificity of Leishman-Donovan bodies (Fig 1, A) for cutaneous leishmaniasis were 76.9% and 100%, respectively.…”

A rare case of pulmonary nocardiasis in an AIDS patient

“…Most cases of nocardiosis present with nonspecific respiratory symptoms such as cough, chest pain, dyspnea, and hemoptysis at presentation, which mimic TB. [7] About 5% of the patients with proven pulmonary TB were shown to have coinfection with nocardia; [8,9] chronic nocardiosis carries a mortality rate of 33% and acute disease shows a rate of 66-72%. [10] In our case, despite the initial suspicion that the patient's lung lesion represented the focus of tuberculous infection, a bacterial pathogen requiring different treatments was identified.…”