Lymph node infection by Trichomonas tenax: Report of a case with co-infection by Mycobacterium tuberculosis

CASE STUDIES

LYMPH NODE INFECTION BY TRICHOMONAS TENAX: REPORT OF A CASE WITH CO-INFECTION BY MYCOBACTERIUM TUBERCULOSIS CHRISTOPHE DUBOUCHER, MD, FERNANDA FARTO-BENSASSON, MD, MIREILLE CHE´ RON, MD, JEAN-YVES PELTIER, MD, FRANC¸OIS BEAUFILS, MD, AND GUY PE´ RIE´ , MD In an 82-year-old woman, presenting with fever and asthenia, cervical adenopathy was noted. Clinical and radiological investigations were fruitless. Laboratory examinations detected a refractory anemia. The lymph node was excised and showed numerous trichomonads on touch preparations. Histologically, the node showed caseous necrosis and macrophagic reaction. Diagnosis of lymph node infection by Trichomonas tenax was made. Three weeks later, culture of the node showed Mycobacterium tuberculosis and let us conclude

co-infection. T tenax is usually regarded as a harmless saprophyte of the oral cavity. This exceptional observation shows for the first time an invasive potential of T tenax. It raises questions about links with tuberculosis and refractory anemia. HUM PATHOL 31:1317-1321. Copyright © 2000 by W.B. Saunders Company Key words: trichomonas, parasitology, parasitic diseases, oral medicine, opportunistic infections.

Trichomonas tenax is an overlooked species of trichomonads, known by some as a commensal of the mouth. A few

years ago, we reported a case of infestation that occurred in a submaxillary gland.1 Only cytologic pictures were obtained. Recently, we had the opportunity to observe a second case in which this parasite was found in a necrotizing adenitis. We present this case showing for the first time the potential of T tenax to invade lymphatic vessels. Pathologists who deal with head and neck region pathology must know this parasite.

From the Department of Pathology, Department of Internal Medicine B, and Laboratory of Bacteriology and Hematology, SaintGermain-en-Laye Hospital, France. Address correspondence and reprint requests to Christophe Duboucher, MD, Laboratoire d’Anatomie Pathologique, Hoˆpital de Saint-Germain-en-Laye. 20, rue Armagis, 78100 Saint-Germain-enLaye, France. Copyright © 2000 by W.B. Saunders Company 0046-8177/00/3110-0019$10.00/0 doi:10.1053/hupa.2000.18502

CLINICAL DATA An 82-year-old woman was hospitalized to explore a febrile asthenia. A painless left infra-auricular lymph node measuring 3 cm was noted. The patient’s temperature was 38.2°C. No wound was found in the edentate mouth. Otorhinolaryn-

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gologic examination showed no malignant tumor. Dental panoramic radiographs could not be performed. A chest radiograph was considered normal. Standard laboratory tests showed mild pancytopenia but no inflammatory syndrome. Refractory anemia was confirmed by bone marrow aspiration showing dysplastic changes of medullar cells, 5% of ringed sideroblasts, and less than 5% of blasts. No cytogenetic studies were performed. Hemoculture and culture of feces were negative, just as serological tests for various infectious diseases: salmonella, brucella, bartonella, rickettsia, and human immunodeficiency virus. No granulomatous lesion was found on marrow biopsy. A needle aspiration of the cervical lymph node was considered as fruitless. The lymph node was then removed and sent unfixed. Whole section showed large patchy necrosis. Touch preparations made for a rapid answer showed a protozoan recognized as T tenax, which was retrospectively found in the needle aspiration performed previously. A fresh fragment was dispatched to culture for protozoa and bacteria. A few days after excision, a cervical effusion was noticed, and a needle aspiration was performed showing trichomonads. A treatment by metronidazole was started. The cervical effusion did not recur, but fever persisted. Three weeks later, a culture of the excised lymph node showed Mycobacterium tuberculosis. Metronidazole was then discontinued, and antituberculosis therapy was initiated. Fever rapidly decreased, but the patient, suffering from general fatigue, died a few weeks later. No autopsy was performed. PATHOLOGICAL DATA Standard Cytologic Examination Needle aspiration and touch preparations of the lymph node stained by May-Gru¨nwald-Giemsa (MGG) showed a predominance of small lymphocytes mixed with some macrophages, plasma cells, large lymphoid cells, neutrophils, and rare eosinophils. Elsewhere, a careful examination showed numerous protozoans occurring singly or in clusters. Most of them, measuring 6 to 12 ␮m, had a suggestive appearance with an oval-shaped nucleus and a blue cytoplasm, well or ill-defined, and containing red granulations (Fig 1). Amoeboid forms were also found, showing abundant dark cytoplasm with vacuoles. Some parasites were also found in the scraping of the denture and in the cervical effusion that developed after lymph node excision. Standard Histologic Examination On histologic section of the formalin-fixed lymph node, large areas of caseous necrosis filled all the central part. A wide zone composed predominantly of macrophages lined the central necrosis, mixed with epithelioid cells. Some giant cells were found but did not show the Langhans type. This inflammatory zone extended into adipose tissue and contained foci of fibrinoid necrosis surrounded by macrophages and epithelioid cells. Careful examination of the macrophagic zone showed small cells which possibly correspond to parasites, with a finely outlined nucleus and sometimes tiny red granulations on Giemsa stain (Fig 2). Periodic acid-Schiff (PAS) stains do not bear more details. By the modified Bodian silver stain adjusted to protozoology2 and quickened by microwave, we could not reveal the parasite. Ziehl-Nielsen stain was negative on the first slides. Nevertheless, after the positive result of the culture, ZiehlNielsen stain was carried out on new slides and showed some aggregates of acid-fast bacilli (Fig 3).

Immunohistochemistry A series of sera have been applied on paraffin embedded slides against the following antigens and remained negative: Trichomonas vaginalis (Argene, Varilhes, France), Pneumocystis carinii, Toxoplasma, cytomegalovirus, and herpes I and II. Electron Microscopy Fragments of lymph node preserved in formalin were routinely processed for electron microscopy. Parasites were found in the macrophagic area. They present with scalloped margins and oval-shaped nucleus with homogeneous chromatin (Fig 4). Unfortunately, no specific structure could be visualized such as flagella, costa, or axostyle. DISCUSSION Three distinct species of trichomonads are found in humans: the genito-urinary T vaginalis, the intestinal Trichomonas hominis, and the oral T tenax.3 Apart from the classical well known ovoid flagellated form observed on fresh and unstained preparations, other aspects have been described in vivo or in vitro: a plasmodium-like form without flagella, an amoeboid form, and a giant multinucleated form. Trichomonads are easily found on stained smears but are almost invisible on histological sections. Thus, clinician and pathologist should be aware that trichomonads might be implicated, and appropriate examination of smears should be conducted. MGG stain is more efficient than Papanicolaou stain for detection of trichomonads on smears and shows more details. Special histochemical techniques that are adequate for identification of bacteria, fungi, and parasites on histologic sections (Gram, PAS, and Grocott) do not show trichomonads. Giemsa stain can show some details. Bodian modified silver stain, which has been useful for others,2 remained unsuccessful in our case. No serum has been developed to detect T tenax on histologic sections. We tried without success to label the parasite by cross-reaction with a commercially available monoclonal serum suitable to detect T vaginalis on vaginal smears. Detection of T tenax by polymerase chain reaction has been perfected,4 but to date there is no specific trade probe for in situ hybridization. A useful method to recognize specific features of different species of trichomonads is transmission electron microcopy. Nevertheless, perfect conditions of fixation by glutaraldehyde are needed as our case shows. Culture can help to detect and to identify the species but must be planned before sampling. Failure of culture in our case is probably explained by the delay of seeding. Finally, we identified the parasite as T tenax. This was based on the similar morphology of the parasite from the lymph node and the trichomonads detected in the mouth of the patient, as well as the trichomonads formerly observed on smears from submaxillary gland.1 T tenax is usually regarded as a harmless saprophyte of the mouth in humans; its prevalence is very high.4 T tenax (or trichomonad consistent with T tenax) is sometimes reported elsewhere, in the course of disease of sinuses, esophagus, lung, and pleura. In almost all these conditions, T tenax seems unable to cause disease on its own. A route from mouth can always be marked out. It settles and multiplies in purulent environment. Nevertheless, in quite exceptional observations, T tenax appears pathogenic per se: a case of pneumonia with eosinophilia,5 an indolent swelling of a submaxillary gland,1 and a case of eosinophilia with bronchial pullulating of T tenax.6 Lastly, presence of T tenax has recently been noticed in fibrocystic mastopathy.7 In the present case, invasion of oral mucosa and progres-

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FIGURE 1. (A) A group of 6 trichomonads with vanishing cytoplasm. (MGG, original magnification ⫻ 1000.) (B) An isolated trichomonad with preserved cytoplasm and reddish granules. (MGG, original magnification ⫻ 1000.)

sion from mouth to lymph node through lymphatic vessels has been an obligatory step. The edentate patient had no wounds in the mouth nor stumps that could explain penetration. No fistula was noted between lymph node and mouth. It can be assumed that T tenax was restricted to the removed infra-auricular lymph node and that other symptoms were linked to tuberculosis. This can be inferred from the ability of the antituberculosis therapy to improve the patient’s condition, whereas metronidazole given alone over 3 weeks was unsuccessful. This case shows invasive potential of T tenax. T vaginalis or unspecified trichomonads have sometimes been noticed in blood.7,8 Invasive potential of T vaginalis has been shown in recent years by immunoperoxidase procedure. By this way, pres-

ence of T vaginalis has been ascertained in the stroma of prostate9 and in the subepithelial tissue of uterine cervix.10 Two reports describe T hominis in amoebic liver abscesses.11 Nevertheless, until now, invasion by T tenax has never been reported. In our case, specific picture of T tenax invasion could be distinguished despite co-infection by M tuberculosis. Macrophagic type reaction—instead of epithelioid—and fibrinoid necrosis are unusual for tuberculosis. Moreover, trichomonads were found in the wide inflammatory ring composed of macrophages. This pattern has been described in comparable pathological findings of invasive trichomoniasis associated with caseous necrosis.12 Thus, caseous necrosis can be attributed not only to M tuberculosis but possibly also to T tenax.

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FIGURE 2. Inflammatory zone with macrophages and small cells considered as parasites (arrows), with minute red granules. (Giemsa, original magnification ⫻ 1000.)

A link between trichomoniasis and tuberculosis is likely. It seems logical that an erratic trichomonad has settled in a node close to the mouth and previously infected by M tuberculosis. Caseous necrosis, if linked to tuberculosis in the present case, would have facilitated settlement by T tenax. A link between trichomoniasis and myelodysplasia or immunodeficiency can be argued by 3 recent reports in human pathology: (1) a peritonitis in an immunocompromised patient caused by Trichomitus fecalis, species known in batrachians13; (2) a meningoencephalitis after blood stem transplantation caused by Trichomonas foetus, species known by infections of cattle14; and (3) an esophagitis with an unidentified species in a patient suffering from acquired immune deficiency syndrome.15 Nevertheless, these observations are too exceptional

to charge immunodeficiency. In another hypothesis, we can suppose that we deal with a virulent strain. Probability of such virulent strains is illustrated by comparative pathology. No case of lymph node trichomoniasis by T tenax, T vaginalis, or T hominis has been reported in literature. We believe that it reflects the lack of search rather than extreme rarity. For the second time we have observed the overlooked parasite T tenax in samples from the head and neck region. The 2 conditions necessary for diagnosis have been fortunately combined: smears colored by MGG and awareness of the parasite. Perhaps the reported case does not represent the standard description of invasive trichomoniasis by T tenax. Finding of other cases will help to define pathogenicity of this parasite, patterns of invasion, and links with pre-existing lesions and immunodeficiencies.

FIGURE 3. A cluster of acid-fast bacilli in caseous necrosis. (Ziehl-Nielsen, original magnification ⫻ 1000.)

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FIGURE 4. Two parasites observed by TEM. (original magnification ⫻ 7000.)

Acknowledgment. The authors wish to thank MarieThe´re`se Macaire, Marianne Rona, Rene´ Lay Kuen, and Jacques Paray for their technical assistance.

REFERENCES 1. Duboucher C, Mogenet M, Pe´rie´ G: Salivary trichomoniasis: A case report of infestation of a submaxillary gland by Trichomonas tenax. Arch Pathol Lab Med 119:277-279, 1995 2. Levine ND: Veterinary Protozoology. Ames, Iowa, Iowa State University Press, 1985, pp 372-373 3. Honigberg BM: Trichomonads Parasitic in Humans. New York, NY, Springer Verlag, 1990 4. Kikuta N, Yamamoto A, Fukura K, et al: Specific and sensitive detection of Trichomonas tenax by the polymerase chain reaction. Lett Appl Microbiol 24:193-197, 1997 5. Khanin AL, Staroverova LL: Retsidiviruiushchaia e´ozinofil’naia pnevmoniia i eozinofiliia krovi pri trikhomonal’nom bronkhite. Klin Med (Mosk) 60(11):95-97, 1982 6. El Kamel A, Rouetbi N, Chakroun M, et al: Pulmonary eosinophilia due to Trichomonas tenax. Thorax 51:554-555, 1996

7. Krvavac S: Trichomoniasis of the breast diseased by fibrocystic mastopathy: Pathogenic rather than saprophytic relationship. Med Arh 52:143-145, 1998 8. Hees E: L’ascension du Trichomonas vaginalis. Gyne´cologie et Obste´trique (Paris) 34:191-200, 1936 9. Gardner WA Jr, Culberson DE, Bennett BD: Trichomonas vaginalis in the prostate gland. Arch Pathol Lab Med 110:430-432, 1986 10. Gardner WA Jr, Culberson DE, Stafford JR: Subepithelial organisms in trichomonal cervicitis. Diagn Cytopathol 3:227-229, 1987 11. Jakobsen EB, Friis-Møller A, Friis J: Trichomonas species in a subhepatic abscess. Eur J Clin Microbiol 6:296-297, 1987 12. Bunton TE, Lowenstine LJ, Leininger R: Invasive trichomoniasis in a Callicebus moloch. Vet Pathol 20:491-494, 1983 13. Straube E, Ockert G, Koch H, et al: Peritonitis caused by trichomonas—A preliminary case report. Zentralbl Mikrobiol 275:394-396, 1991 14. Okamoto S, Wakui M, Kobayashi H, et al: Trichomonas foetus meningoencephalitis after allogenic peripheral blood stem cell transplantation. Bone Marrow Transplant 21:89-91, 1998 15. Borczuk AC, Hagan R, Chipty F, et al: Cytologic detection of Trichomonas esophagitis in a patient with acquired immunodeficiency syndrome. Diagn Cytopathol 19:313-316, 1998

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