title: Immunocytochemical detection of mycobacterial antigen in extrapulmonary tuberculosis.
abstract: The aim of the study is to determine whether immunostaining for mycobacterial antigen can contribute to the cytological diagnosis of extrapulmonary tuberculosis (EPTB). The study was carried out on aspirated material of lymph nodes, and other accessible sites, from 65 patients with clinical diagnosis of tuberculosis (TB). Twenty patients, diagnosed by fine-needle aspiration, with non-tuberculous granulomas served as controls. The diagnosis of TB was based on the demonstration of acid-fast bacilli (AFB), culture positivity for Mycobacterium tuberculosis (M. tuberculosis), or response to treatment with standard anti-tubercular therapy. Immunostaining was done using polyclonal antibody to mycobacteria. AFB positivity by Ziehl Neelsen (ZN) staining was 21%, 65.38%, and 68% respectively in Pattern 1 (granulomas alone), in Pattern 2 (granulomas with necrosis), and in Pattern 3 (necrosis alone). Overall AFB positivity was 56.92%. Twenty-eight of 65 cases were negative for AFB on direct smear. Culture was positive in 46% (13/28). Sensitivity and specificity of immunostaining were 96.92% (63/65) and 95%, respectively. Immunoreactivity was seen in 26 (92.8%) of 28 cases which were negative by ZN staining. Except in the case of leprosy, in which cross reactivity was seen, there was no immunoreactivity in the control group. Immunocytochemistry (ICC) had high sensitivity (96.2%) and specificity (95%) in the diagnosis of EPTB. ICC may be a useful adjunct to evaluation of cytomorphology and ZN staining.
authors.affiliation: Department of Pathology, UCMS & GTB Hospital, Shahdara, Delhi, India.
authors.forename: Pooja
authors.initials: P
authors.lastname: Prapanna
authors.forename: Ruchi
authors.initials: R
authors.lastname: Srivastava
authors.forename: Vinod Kumar
authors.initials: VK
authors.lastname: Arora
authors.forename: Navjeevan
authors.initials: N
authors.lastname: Singh
authors.forename: Arati
authors.initials: A
authors.lastname: Bhatia
authors.forename: Iqbal R
authors.initials: IR
authors.lastname: Kaur
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000942:Antigens, Bacterial / Q000032:analysis*; D000995:Antitubercular Agents / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003429:Cross Reactions; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000276:immunology*; D012680:Sensitivity and Specificity; D013194:Staining and Labeling / Q000379:methods; D014388:Tuberculosis, Lymph Node / Q000175:diagnosis* / Q000188:drug therapy / Q000382:microbiology / Q000473:pathology
chemical_list: D000942:Antigens, Bacterial; D000995:Antitubercular Agents
keywords: extrapulmonary tuberculosis; fine-needle aspiration; immunocytochemistry