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Isolated Hydatid Disease of the Breast: Fine‐Needle Aspiration Cytologic Diagnosis in a Clinically Unsuspected Case

Hydatid disease is mainly caused by the larva of Echinococcus granulosus and it is endemic in many parts of the world like in India. Humans are the accidental intermediate hosts of this organism. Liver and lungs are the most commonly affected organs and breast is a rare primary site. Isolated involvement by hydatid cyst is still rarer. We report a case of hydatid cyst of the breast, which was diagnosed preoperatively on fine-needle aspiration cytology (FNAC), but was clinically unsuspected of hydatid disease. The case was further correlated radiologically. A 45-year-old woman presented with complaint of a gradually progressive lump in left breast since 1 year. On physical examination, a well-defined, round, 2 9 2 cm, mobile, nontender lump was palpable in the upper outer quadrant of the left breast (UOQLB). No other lump was found in contralateral breast and bilateral axillae. Clinical picture was suspicious of breast abscess or malignant breast pathology and thus referred for FNAC. Fine-needle aspiration cytology from the breast lump yielded thick whitish aspirate and the smears showed fragments of acellular lamellated membranous structures with delicate parallel striations along with dispersed multiple tri-radiate hooklets in a necrotic background along with an occasional cluster of benign breast epithelial cells at some places (Fig. 1). The cytomorphologic findings were diagnostic of hydatid cyst. Patient was advised for further radiologic correlation and for lesion at any other site. Ultrasonography of the breast revealed a thinwalled, well-defined, cystic lesion without internal echoes in UOQLB close to the pectoral major fascia, measured 2.8 9 2.3 cm in size and showed clumped membrane-like structures within the cyst (Fig. 2). Radiologically, the chest and abdomen were normal and revealed no other cysts at any other site in the body. The patient was advised for surgical intervention along with a course of antihelminthic drug. Human hydatid disease is endemic in India and cases of hydatid have been reported from all parts of the country. The most commonly affected organs are the liver (70%) and lungs (25%); the less frequently affected sites are the spleen, kidneys, heart, bone, nervous system, and soft tissue. Breast involvement is rare, accounting for only 0.27% of the localizations. It can be the primary site or part of disseminated hydatidosis and usually presents as a painless, slowly progressively increasing breast lump. The symptoms and signs are nonspecific and thus the clinical suspicion is rare. Preoperative diagnosis of mammary hydatid disease has been made accurately on the basis of FNAC, in the presence of pathognomic hooklets and the laminated membrane. Radiologically, ultrasonography is more specific than mammography in identifying a hydatid cyst. The sonographic findings of mammary hydatid cysts are similar to those seen in other organs and reveal a well-defined, lobulated mass of heterogeneous echogenicity that may contain multiple cystic areas. Due to the rareness of this condition, the above-mentioned sonographic appearance of breast hydatid disease is frequently missed until aspiration cytology or an operative diagnosis has been Address correspondence and reprint requests to: Dr Nivedita Ghosh, Department of Pathology, Maulana Azad Medical College, Bahadur Shah Zafar Marg, New Delhi 110002, India, or e-mail: nivedita3004@gmail.com