Cytodiagnosis of coexistent cryptococcal and mycobacterial lymphadenitis in a case of AIDS.

Multiple infections are a common feature of acquired immunodeficiency syndrome (AIDS), but coexistent infections at the same site are rare. In this report, we describe a 35-year-old human immunodeficiency virus infected male with coexistent cryptococcal and mycobacterial lymphadenitis. He presented with generalised lymphadenopathy. Fine needle aspiration cytology of enlarged cervical lymph node, aided by special stains, revealed coexistent cryptococcal and mycobacterial infection. Coexistent infections pose diagnostic problems in AIDS patients and are likely to be missed. Special stains are valuable for accurate diagnosis of coexistent infections.

Introduction

Patients with acquired immunodeficiency syndrome (AIDS) are prone to a variety of opportunistic infections. Both mycobacterial as well as cryptococcal infections are commonly found in these patients. But simultaneous lymph node involvement by this dual pathology is extremely rare. We report a case of AIDS having coexistent mycobacterial and cryptococcal lymphadenitis which was diagnosed on fine needle aspiration cytology (FNAC).

Case Report

A 35-year-old male presented with the complaints of evening rise of fever, cough with expectoration, and hemoptysis since 2 months. On examination, he was found to have enlarged, firm, nontender lymph nodes in cervical, axillary and inguinal regions. Laboratory investigations revealed a hemoglobin level of 10 g/dl, white blood cell count of 3000/mm3 with 70% polymorphs, 25% lymphocytes, 1% eosinophils and 4% monocytes and an erythrocyte sedimentation rate of 28 mm at the end of 1 hour. Enzyme-linked immunosorbent assay (ELISA) test for human immunodeficiency virus (HIV) was reactive for HIV I and HIV II and the CD4 count was 27/μl. FNAC of the cervical lymph node was studied with hematoxylin and eosin (H and E), periodic acid Schiff (PAS), mucicarmine, Gomori's methanamine silver (GMS) and Ziehl Neelsen (ZN) stains.

Cytological findings

The smears were cellular and showed epithelioid granulomas, foci of caseous necrosis and few lymphocytes. The background showed variably sized, rounded, budding yeast cells with refractile capsule morphologically suggestive of cryptococci [Figure 1]. PAS, GMS and mucicarmine positivity confirmed the organisms as cryptococci [Figures 2 and 3]. The smears stained with ZN stain showed the presence of few acid fast bacilli [Figure 4]. A diagnosis of coexistent cryptococcal and mycobacterial lymphadenitis was rendered. FNAC aspirate was inoculated on Sabourauds dextrose agar and Lowenstein Jensen (LJ) medium. White, round, moist, convex colonies appeared on Saborauds dextrose agar after 48 hours of incubation, the Gram stain of which showed capsulated yeast cells. A positive urease test confirmed the growth as Cryptococcus neoformans. LJ medium did not show growth even after 14 weeks of incubation.

Figure 1

Photomicrograph showing epithelioid granuloma and caseous necrosis with cryptococci in the background (H and E, ×400)

Figure 2

Silver stain highlighting the cryptococci (Gomori's methanamine silver stain, ×400)

Figure 3

Smear showing the carminophilic capsule of cryptococci (Mucicarmine stain, ×400)

Figure 4

Smear showing acid fast bacillus (Ziehl Neelsen stain, ×1000)

Discussion

FNAC is a valuable investigation for HIV infected patients with lymphadenopathy. Most of the opportunistic infections and neoplasms can be correctly identified on FNAC. Various cytological studies of HIV lymphadenopathy have indicated that tuberculosis is the most common opportunistic infection in these patients in India.[1] There are also a few cytology case reports of cryptococcal lymphadenitis.[2] However, to the best of our knowledge, there is no report of coexistent mycobacterial and cryptococcal lymphadenitis diagnosed on FNAC.

Simultaneous and multiple pathologies is a feature of AIDS, but coexistent diseases occurring at the same site are rarely documented. Jayaram and Chew,[3] in their FNAC study of 39 cases with HIV lymphadenopathy, found a single case of concomitant infection of lymph node with mycobacteria and Penicillium marneffei.

The literature search also reveals reports of dual infection of lymph node with Mycobacterium tuberculosis and Pneumocystis jiroveci, concomitant tuberculous and cryptococcal meningitis, coexistent Kaposi sarcoma, cryptococcosis and Mycobacterium avium intracellulare in a solitary cutaneous nodule and coexistent cutaneous cryptococcosis and molluscum contagiosum.[4-7]

Our case presented with generalised lymphadenopathy and the FNAC smears revealed epithelioid granulomas, foci of caseous necrosis and numerous capsulated yeast forms of cryptococci. The yeast forms of cryptococci need to be differentiated from Candida species (spp.) Blastomyces dermatitidis and Histoplasma capsulatum, particularly when they are poorly encapsulated. The presence of pseudohyphae gives a clue for the diagnosis of Candida spp. B. dermatitidis shows broad based budding in contrast to cryptococci which show narrow based budding. With H and E stain, the yeast cell of H. capsulatum appears to be surrounded by a halo which may be mistaken for capsule. However, this halo is not seen with special stains like GMS.[8] In our case, mucicarmine positivity was diagnostic of cryptococci and cultural study confirmed the presence of C. neoformans.

The ZN stained smears revealed few acid fast bacilli. However, the species identification of mycobacterium was not possible due to culture negativity. The rate of culture positivity of aspirates from lymph nodes with mycobacterial lymphadenitis in different studies has ranged from 18% to 62%.[9] Culture negativity has been attributed to the inhibitory effect of prior broad spectrum antibiotics or anti tuberculosis treatment. There can also be a possibility for the presence of nonviable or very few viable organisms that were missed by culture.[10]

In conclusion, FNAC is a safe, simple and useful technique with the advantage of rapid diagnosis. Although culture is important in the identification of pathogen, the diagnosis can be made on cytologically obtained smears. The possibility of coexistent infections should always be kept in mind and a battery of special stains should be employed on the aspirates of HIV infected patients for a complete and accurate diagnosis, as it has therapeutic implications.