Pulmonary echinococcosis with Actinomycetes-like organisms mimicking malignancy: Diagnosed by fine needle aspiration cytology.

Sir,

Superimposed fungal or bacterial infections are known to occur in pre-existing lung cavities secondary to tuberculosis, bronchial cysts and bullae, pulmonary tumors or infarction. Fungal infections such as Aspergillosis have been described previously in a hydatid cyst. We here describe the rare occurrence of Actinomycetes-like organisms growing in a hydatid cyst diagnosed on fine needle aspiration cytology in an immunocompetent patient.

A 50-year-old female patient presented with a history of cough and expectoration associated with hemoptysis for 3 months. Human immunodeficiency virus serology was negative. Contrast enhancing computed tomography chest revealed a 3 cm diameter well-defined heterogeneous peripherally enhancing lesion with irregular borders in the right lower lobe of lung [Figure 1a]. The differential diagnoses considered on imaging were bronchogenic carcinoma or a pulmonary abscess. Computed tomography guided fine-needle aspiration was performed, which yielded about 1.5 mL of thin necrotic pus-like material. The sediment as well as direct smears were prepared. The smears were stained with May-Grünwald-Geimsa (MGG), H and E, Papanicolaou, Periodic acid-Schiff's (PAS) and Ziehl-Neelsen stains. Smears revealed multiple fragments of amorphous lamellated hyaline acellular PAS positive membranes [Figure 1b–d] and hooklets of Echinococcus granulosus [Figure 1d, Inset]. In addition, numerous thin delicate filamentous organisms were seen growing over the lamellated membranes. One of the MGG stained smear was destained and stained with the Gram stain. These filamentous organisms were Gram-positive consistent with morphology of Actinomycetes-like organisms. Sheets of acute inflammatory cells and foamy macrophages were seen in the background of the smear; however, no epithelioid cell granulomas were noted. Part of the pus like material was also processed with SurePath™ liquid based cytology technique [Figure 1d]. The cytologic diagnosis offered was pulmonary echinococcosis with superadded Actinomycetes-like organisms. Culture was not sent as the possibility of malignancy was high clinico-radiologically at the time of aspiration. Patient was given a high dose of sulfamethoxazole and trimethoprim, therapy for 6 weeks and albendazole therapy 400 mg twice daily and later was subjected to surgery of the hydatid disease. The histopathology revealed only hydatid cyst and Actinomycetes-like organisms were not seen as histopathology was done after treatment. At present, the patient is doing well.

Figure 1

(a) Contrast enhancing computed tomography chest showing a well-defined heterogeneous peripherally enhancing 3 cm lesion with irregular borders in right lower lobe of lung with in-situ fine needle aspiration needle; (b) Hyaline membrane of hydatid cyst with dense acute inflammatory infiltrate (MGG, x200); (c) Amorphous acellular hydatid membrane with filamentous bacteria (MGG ×400); (d) Liquid based cytology smear showing hyaline laminated hydatid membranes (MGG ×40), Inset-Hooklet of hydatid (Pap, ×400)

Lung is the most common site of involvement by hydatid disease. Pulmonary hydatid cyst may rupture into the bronchial tree and produce cough, chest pain, or hemoptysis. At this stage, it is difficult to diagnose on imaging due to atypical features.[1] Pulmonary actinomycosis is a rare bacterial disease and it occurs due to poor oral hygiene, which allows the normal flora to proliferate. Aspiration of the infected material is the presumptive mechanism that leads to thoraco-pulmonary infection.[2] Diagnosis of dual or multiple infections of the respiratory tract by fine needle aspiration cytology (FNAC) has been documented in a few case reports especially in immunocompromised patients.[34] There is only one previous case report of diagnosis of these two dual infections/infestations diagnosed on FNAC.[5] We report a rare case of pulmonary hydatid disease complicated with Actinomycetes-like organisms diagnosed on FNAC, radiologically mimicking bronchogenic carcinoma. Although FNAC is contraindicated in suspected hydatid disease, this case highlights the role of FNAC in the diagnosis of two rare lung infections in this case, prompting an early and sucessful treatment.