Coexistent axillary hydatid disease and tuberculosis: Case report of an extremely rare occurrence

Abstract

Tuberculous infection is highly prevalent in India, however, hydatid disease is relatively uncommon. Frequent sites of predilection of hydatid disease are the liver and lungs. Other unusual sites of infliction are the peritoneum, thyroid, breast, pancreas, and mediastinum. Hydatid disease in the axilla is quite uncommon. We hereby report a case of coexistent axillary hydatid disease with tuberculous lymphadenitis. To the best of our knowledge, even after extensive search of the literature we did not come across any such case. Fine needle aspiration cytology (FNAC) is a cost-effective procedure performed on an outpatient basis and helped clinch a prompt diagnosis, with minimum discomfort or complications. The role of FNAC in early diagnosis cannot be overemphasized.

Introduction

Hydatid disease is an important zoonotic disease of man as a result of infection caused by the larval form of Echinococcus granulosus. Although a problem of global dimensions, it is endemic in the Mediterranean region of Asia.[1,2] In the Indian subcontinent, a higher prevalence has been reported in Andhra Pradesh, Tamil Nadu, Gujarat, and West Bengal.[2] It is known to localize classically in the liver and lungs, although multiorgan involvement has been noted in 10% of the cases.

The hydatid cyst has previously been reported in the axilla, rarely.[3,4,5,6] Coexistence of an incidental hydatid cyst with tuberculous lymphadenitis on cytology has not been reported so far, to the best of our knowledge. After extensive search of literature, we found that coexistence of both these infections have been reported in the lung only.[7,8] We present a case of this extremely rare combination, which was promptly diagnosed using a minimally invasive, relatively inexpensive investigative procedure, like fine needle aspiration cytology (FNAC).

Case Report

A 32-year-old male presented to the surgical clinic with multiple left axillary lymph nodes. His complaints had been persistent for the previous eight months and had been preceded by development of furuncles in the axilla. Although he had infrequently taken treatment from several practitioners, there was no relief to his complaints. He subsequently developed fever ranging from 100-101° F. There was no family or past history of tuberculosis or loss of weight or appetite. Jaundice was not present.

The patient had a negative Montoux test. Hematological evaluation revealed a raised erythrocyte sedimentation rate (ESR) of 28 mm in the first hour by the Wintrobes method. Other hematological parameters, including a coagulation profile, were normal. The chest radiograph did not reveal any abnormality. Liver function tests showed the total bilirubin level to be 0.7 mg/dL, serum alkaline phosphatase was 52 U/L, and serum alanine and aspartate aminotransferases were 21 U/L and 28U/L, respectively. The patient was referred to the Department of Pathology for FNAC, with a provisional diagnosis of tuberculosis, a disease rampant in rural as well as urban India. On palpation, three lymph nodes were discernible in the left central axilla which were discrete, firm, and mobile, ranging in size from 0.8 to 2.0 cm, with pain in the largest one. FNA was performed on the largest lymph node.

A blood-tinged caseous aspirate was obtained and several fixed and dry smears were prepared, which were stained with hematoxylin and eosin, Giemsa, and Ziehl Neelson (ZN) stains.

Smears were cellular showing intact and degenerated neutrophils, histiocytes, and eosinophils, along with several loose epithelioid cell granulomas, giant cells, and a variable number of lymphoid cells [Figure 1a]. The background showed extensive caseous necrosis. When the ZN stained smears were being screened for the presence of acid fast bacilli, classical hooklets of Echinococcus were noticed [Figure 2a]. The hooklets were semi-translucent, retractile, and sickle-shaped, with an inner semi-translucent core of a similar shape. Alerted by this discovery, a further search revealed scolices of Echinococcus, which were large ovoid structures [Figure 2b]. However, no lamellated membrane was identified. In addition, classic granular, beaded, acid fast bacilli of Mycobacterium tuberculosis were seen [Figure 1b]. This enabled us to render a diagnosis of tuberculous lymphadenitis with coexistent echinococcal infection.

Figure 1a.

Photomicrograph showing epithelioid cell granuloma in a background of blood admixed with necrosis (Giemsa, ×400)

Figure 2a.

Photomicrograph showing the semi-transluscent, refractile hooklet of Echinococcus (Ziehl Neelsen Stain, ×1000)

Figure 2b.

Photomicrograph showing scolex of Echinococcus (ZN Stain, ×400)

Figure 1b.

Photomicrograph showing acid fast bacilli of Mycobacterium tuberculosis, marked by arrow (Ziehl Neelsen Stain, ×1000)

An ultrasound of the abdomen was unremarkable. Contrast-enhanced computed tomography was advised for the chest as well as liver, which the patient could not afford. The echinococcal indirect hemagglutination test was negative. Retrospectively, the patient gave a history of contact with a dog. Polymerase chain reaction as well as culture for Mycobacterium tuberculosis was positive. Antihelminthic as well as anti-tuberculous therapy was started. However, the excision could not be performed as the patient was lost to follow-up.

Discussion

Tuberculosis and hydatid disease are public health problems worldwide. India has the highest burden of tuberculosis in the world, with approximately 1.8 million people developing the disease annually.[2] The incidence of hydatid disease, an important zoonotic disease of man, is high in sheep-raising countries like New Zealand, Turkey, Australia, and so on. In India, the pockets of high prevalence are Andhra Pradesh, Tamil Nadu, Gujarat, and West Bengal.[2] The lungs and liver are primary sites of localization for the hydatid disease, however 10% are reported to occur in unusual sites such as the peritoneum,[9] thyroid,[10] submandibular gland,[10] breast,[11] pancreas,[12] pericardium,[12] parotid gland,[13] and the supraclavicular soft tissue.[14] The involvement of Echinococcus granulosus in children has a different pattern compared to adults, as the lungs are more commonly affected than the liver. However, there are a few case reports of multiple hydatid cysts of the liver in children.[15]

Axillary hydatid disease is rare. Coexistence of hydatid disease and tuberculosis is still more rare. Search of the literature revealed two case reports of pulmonary hydatid cysts with tuberculosis, both from Turkey, a region noted for a high prevalence of hydatid disease.[1] In both the cases, radiological findings coupled with histopathology helped render the final diagnosis. In the present case the diagnosis was achieved using a much simpler, easy-to-perform, minimally invasive, and cost-effective modality.

When screening smears of the patient, giant cells, loose epithelioid cell granulomas, and mixed inflammatory infiltrates comprising of neutrophils, histiocytes, and eosinophils were seen against a background of caseous necrosis. Screening of ZN-stained smears for acid-fast bacilli (AFB) revealed structures suspicious of the body wall of a parasite, and eventually, hooklets and scolices of the hydatid were identified along with the AFB. The hooklets were semi-translucent, refractile, and sickle-shaped, with an inner semi-translucent core of a similar shape. Further search showed scolices of Echinococcus, which were large ovoid structures. Handa et al.[16] observed that hooklets are better highlighted with the use of special stains like Masson's, Trichrome, and Ziehl Neelsen. This holds true in our case as well, where the hooklets were initially identified only on the ZN stain.

In the present case, a serological test performed for confirmation of Echinococcus was negative. This finding was similar to that of Yagmur et al.[17] and Ozsoy M,[1] who reported axillary hydatid cysts in variable clinical settings. However, Iynen et al.[14] observed a positive serology in their patient with a supraclavicular primary hydatid. It is important to remember that while a positive hemagglutination reaction can help confirm diagnosis of hydatid, it can be falsely positive and/or negative, and is therefore, of limited value.

When performing FNAC in the axillary region, few possibilities need to be kept in mind, namely lymphoceles, abscess, axillary pad of fat, accessory breast, hematoma, and metastatic lesions. Cytological findings in corroboration with the clinical details will help to arrive at a correct diagnosis.

The necrotic background and identification of one organism should not halt a thorough search for any coexistent pathology. Thus, in endemic areas, one should consider a remote possibility of axillary hydatid disease, with or without tuberculosis.

Alertness and experience of the cytopathologist in picking up subtle clues when screening smears cannot be overemphasized. The role of the ZN stain as a helpful diagnostic adjunct, in not just confirming the presence of AFB, but also picking up parasitic structures, is highlighted in this case. In the present case scenario, FNAC, a cost-effective diagnostic tool, performed on an outpatient basis helped clinch the diagnosis, with minimum discomfort or complications in the patient.