Rare presentation of isolated hydatid disease of the breast

Background

Hydatid disease is most prevalent in Andhra Pradesh and Tamil Nadu in India.1 The disease is caused by Echinococcus granulosus species, most commonly found in sheep and cattle. Humans are the accidental intermediate host. The most common site in humans is liver (75%) and lungs (15%).2 Uncommon organs include the spleen (5%), brain and breast. Hydatid disease has been reported in the past, poses a diagnostic dilemma for the clinician. It mimics fibroadenoma, cystic mastopathies, phyllodes tumour or chronic breast abscess. It is essential to identify this condition because the cyst’s antigen can cause a significant anaphylactic reaction if appropriate measures are not taken during surgery.

Ultrasound is beneficial to identify cyst morphology. An ultrasound-guided aspiration can also be performed for cytology to rule out other causes.3 A CT scan can be helpful in undetermined cases. An X-ray of the chest, CT and ultrasound of the abdomen are also essential to rule out systemic disease. Specific antibodies against hydatid antigen (immunodiagnostic test) are also helpful in establishing the diagnosis.

Most patients are benefited from a course of albendazole before the operation to control the systemic disease. The breast cyst is removed intact without rupturing the cyst cavity.

Case presentation

A 32-year-old, non-lactating woman presented to the outpatient department reporting of a progressively enlarging, painless lump in the upper outer quadrant of the left breast for the past 2 years. There was no associated nipple discharge or history of trauma to the breast. No record of fever could be elicited. There is no other swelling noted elsewhere in the body. No family history of breast cancer was present.

On examination, an 8 cm×8 cm, rounded, non-tender, smooth-surfaced swelling was present in the breast’s upper, outer quadrant with a positive transillumination test. There was no discharge from the nipple expressed on pressing. The rest of the left breast, right breast and bilateral axillae were normal.

The blood examination was unremarkable. The ultrasonography of the breast revealed an 8 cm×6 cm cystic swelling with clear fluid and smooth margins (figure 1). A mammogram revealed a simple cyst with posterior acoustic enhancement (Breast Imaging-Reporting And Data Systems II, BIRADS II). Aspiration of cyst showed the serous aspirate, which was found to be acellular on microscopy. The microscopy does show scolices and brood capsule. The aspirate tested negative for Mycobacterium spp. ELISA test performed on aspirated fluid was positive for hydatid antigen. Hydatid serology was positive for the antigen. An ultrasound of the abdomen and plain radiograph of the chest done subsequently taken to rule out concomitant lesions, which was reported normal.

Wide local excision of the cyst was performed (figure 2). Intraoperatively, a 7 cm×6 cm subcutaneous cyst was found, revealing clear, serous fluid and a smooth laminated membrane on subsequent sectioning (figure 3). The histopathology examination showed a laminated membrane with daughter cysts suggestive of hydatid disease (figure 4). Postoperatively, the patient was started on albendazole 200 mg two times per day for 6 weeks. The patient completed the course of albendazole successfully and did not show any recurrence sign at the end of 6 months.

Investigations

1. Ultrasound of the breast: Left breast showed 8 cm×6 cm cystic lesion with clear fluid and smooth margins. The right breast and both the axilla are normal.

2. Mammogram: Left breast shows a simple cyst with posterior acoustic shadow (BIRADS II). The right breast is normal.

3. Ultrasound-guided aspiration: Serous aspirate, no cells found.

4. Hydatid serology: Positive for the E. granulosus antigen.

5. Ultrasound of the abdomen: No abnormalities were found.

6. X-ray of the chest: No abnormalities were found.

7. Histopathology of the specimen:

   • Gross: 7 cm×6 cm cystic lesion with clear fluid. A laminated membrane can be seen lining the cyst wall inside.

   • Microscopy: Laminated membrane with daughter cyst can be seen.

Differential diagnosis

We kept cystic mastopathies as our differential diagnosis because of the patient’s age. The patient does not have pain or signs of inflammation which excludes cystic mastopathies and chronic breast abscess. A suspicion of hydatid cyst was made because the swelling was brilliantly transilluminated. A diagnosis of fibroadenoma was excluded as the swelling is cystic with positive fluctuation. A diagnosis of phyllodes tumour was excluded as the patient had no pain or any risk factors.

Treatment

The patient was taken for the wide local excision of the cystic mass. The patient was started on albendazole 200 mg two times per day for 6 weeks postoperatively.

Outcome and follow-up

She showed no signs of remnant disease or recurrence. The patient was fit and healthy at 6 months of follow-up.