Hydatid Cyst of the Breast: A Rare Case Report and Literature Review

ABSTRACT

Breast is a rare location for hydatid cysts, even in endemic regions such as the Middle East. They can mimic more common breast pathologies, such as simple cysts, fibroadenomas, or tumors. So, they warrant careful consideration in any patient with a breast lump. Routine evaluations, such as physical examination, ultrasound, and mammography, rarely identify them as the underlying cause because of the similarity of the manifestations. Definitive diagnosis is usually made intraoperatively, when surgeons identify daughter cysts or the characteristic laminated membrane, or postoperatively through pathological confirmation. Surgical excision is the main treatment, although microscopic examination of cyst fluid pre‐operation can occasionally provide an early diagnostic clue. This report is about a 45‐year‐old woman from northern Iran, in an endemic area. She'd been feeling a painful lump in her left breast for six months when she showed up at our clinic. Exam turned up a single mass in the upper outer quadrant. Ultrasound and mammogram revealed a cyst full of clear, echo‐free fluid, pegged as ACR 2 (BI‐RADS category for likely benign). A needle pull showed just white blood cells, polymorphonuclears, and lymphocytes. No evidence of malignancy. We proceeded with surgery, and partway through, the cyst ruptured and revealed the laminated membrane. The entire cyst was removed, and pathology confirmed it as a breast hydatid cyst. She recovered well after surgery, and follow‐up scans of her liver and chest were clear. We put her on albendazole at 800 mg a day for 3 months, and a year later, there were no signs of relapse. Breast hydatid cyst is a rare condition, even in endemic areas where hydatid diseases are prevalent. Its presentation can easily be mistaken for simple cysts, fibroadenomas, or malignancies. Recurrence is common after the first drainage, so careful management is very important in endemic regions, and physicians should keep parasitic causes in mind. Surgery combined with albendazole is the main treatment and can reduce recurrence risks. Other reviews are consistent with this and show that this treatment has good outcomes, especially when detected early.

Key Clinical Message

Hydatid cysts in the breast are very rare but in areas where this disease is common, they are important to consider. Diagnosing it early and treating it properly with surgery and medication can really help patients recover well and decrease the probability of relapse.

1. Introduction

Breast masses frequently present in clinical settings, ranging from benign cysts to malignant tumors, and are commonly associated with hormonal changes during reproductive years [1, 2]. They typically appear as smooth, mobile lumps, which are detected incidentally on physical exams or mammographic screening, and may sometimes be tender or painful [3, 4]. Diagnostic tools such as ultrasound, mammography, fine‐needle aspiration (FNA), or biopsy are essential for evaluation, although differential diagnoses remain challenging [4, 5, 6].

In endemic areas, parasitic infections like hydatid disease make this more challenging, while they can mimic common breast pathologies [7, 8]. This zoonotic condition is prevalent in regions with close human‐animal contact, such as the Mediterranean, Middle East including Iran, Africa, Australia, and South America, and it primarily affects the liver (50%–77%) and lungs (18%–35%) but occasionally can affect other sites [9, 10, 11]. Complicated liver hydatid cysts often involve intra‐abdominal or intrabiliary ruptures, which can highlight the disease's potential for severe manifestations in endemic settings [12]. Similarly, studies from northern Iran report high morbidity from such complications, although surgical interventions can yield good outcomes despite postoperative risks [13].

Primary hydatid cysts of the breast are very rare and their incidence is below 0.27%, even in high‐risk areas. They can easily be misdiagnosed as fibroadenomas or simple cysts due to nonspecific imaging features [14, 15, 16]. Recent case reports highlight these challenges: one describes a primary breast hydatid cyst that first appeared as a mysterious mass and was only resolved surgically [1], while another showed successful preoperative diagnosis using cytology [17]. These examples, along with reviews from Iran, highlight the need for a careful suspicion in endemic populations to avoid delayed diagnosis [2, 4].

This case report describes a breast hydatid cyst that mimicked a benign lesion and recurred after aspiration, which can highlight the diagnostic challenges and effective management strategies.

2. Case Presentation

A 45‐year‐old woman from a rural area in the endemic Gilan province of Iran presented with a chief complaint of swelling or a mass in her right breast. Her past medical history and drug history were unremarkable. Five months ago, she found a nodule in her right breast during self‐examination. The nodule gradually increased in size, but she mentioned no pain, no nipple discharge, or signs of local inflammation. The patient reported no prior trauma to the breast or history of breast surgery, but she had a history of lactation and the related changes in breast tissue. She also denied any family history of breast malignancies or other hereditary breast conditions. She did not report any systemic symptoms such as fever, weight loss, or fatigue, and there was no nipple retraction or deviation. On physical examination, a well‐defined mass was found in the upper outer quadrant of the right breast, measuring about 5 × 3 cm at its largest. On examination, the mass was firm, well‐circumscribed, mobile, and painless. The overlying skin and surrounding breast tissue appeared normal. Detailed evaluation of the axilla and supraclavicular fossa revealed no palpable lymph nodes or masses, and no axillary or supraclavicular lymphadenopathy was observed (Figures 1, 2).

FIGURE 1.

Now shows the fine‐needle aspiration procedure with clear needle placement.

FIGURE 2.

Depicts the aspirated clear fluid in a sterile container, with no sediment visible.

Ultrasonography and mammography of both breasts and axillary regions was performed. These studies showed no microcalcifications or wall thickening, which could suggest a benign lesion.

Ultrasonography of the right breast revealed a well‐defined, oval, fluid‐filled lesion that measured 4 × 3 cm in the upper outer quadrant. The lesion contained anechoic fluid without internal echoes or septations, and color Doppler confirmed the absence of internal vascularity. Mammography also confirmed these findings and showed the same 4 × 3 cm well‐circumscribed cystic mass without microcalcifications or wall thickening. Based on these imaging findings, the lesion was classified as BI‐RADS 3, indicating a probably benign process (Figures 3, 4, 5).

FIGURE 3.

(USG transverse view) with an arrow to a 4 × 3 cm cyst and measurement overlay.

FIGURE 4.

(USG sagittal) highlighting anechoic content.

FIGURE 5.

(Mammogram CC view) with an arrow to a well‐defined mass.

The initial differential diagnoses were simple breast cyst, complicated breast cyst, fibroadenoma, or phyllodes tumor, although the latter two were less likely because it was fluid‐filled. FNA showed a clear fluid that contained only polymorphonuclear cells (PMNs) and lymphocytes, with no tumor cells. After drainage, the patient was discharged with daily vitamin E supplementation (400 mg) (Figures 2, 3).

At a four‐month follow‐up, we noticed that the cyst has relapsed at the original site. Repeat ultrasonography showed increased size to 5 × 4 cm, (Figures 6 and 7) with persistent anechoic content and no septations. After thorough discussion with the patient, we decided to proceed with complete surgical excision. All standard preoperative laboratory tests were within normal limits.

FIGURE 6, 7.

Added for Doppler (no flow) and repeat USG (5 × 4 cm recurrence) with size annotations.

The patient underwent surgical excision of the cyst. During the operation, the lesion was well‐encapsulated, with a thick, whitish wall that measured 5 × 4 cm (Figure 8). We removed it while we were trying to hold the cyst intact without rupture. Upon opening the excised cyst, clear fluid and a laminated membrane were observed. These features strongly suggested a hydatid cyst of the breast (Figure 9). The specimen was sent to the pathology laboratory for confirmation.

FIGURE 8.

Shows the intact cyst exterior (thick whitish wall).

FIGURE 9.

The opened cyst with a floating laminated membrane, under adequate lighting for clear visualization.

Pathologists found the characteristic 3‐layered structure (Figure 10) of a hydatid cyst: an outer acellular laminated membrane (5–10 μm thick, eosinophilic) (Figure 11), an inner germinal (endocyst) layer with attached brood capsules (Figure 12), and numerous protoscolices of Echinococcus granulosus with hooklets (Figure 13). They were all confirming the diagnosis of a hydatid cyst (Figure 1). The patient was started on albendazole 400 mg twice daily based on our protocol. Abdominal ultrasonography and CT scans of the chest, abdomen, and pelvis were done to check for disseminating cystic lesions, especially in the liver and lungs, which are the most common sites for hydatid disease. No additional cysts were found. Follow‐up included periodic ultrasound of both breasts and the abdomen. We educated her about related hygiene measures to avoid reinfection and monitored her regularly over the next 5 years, with no signs of recurrence.

FIGURE 10.

Overviews 3‐layered structure.

FIGURE 11.

Labels outer acellular laminated membrane (eosinophilic, 5‐10 μm).

FIGURE 12.

Inner germinal membrane with brood capsules.

FIGURE 13.

Protoscolices with hooklets (H&E stain).

3. Differential Diagnosis, Investigations, and Treatment

A breast cyst with fluid can have several differential diagnoses, including common benign cysts, abscesses, galactoceles, and malignant tumors with cystic components. In endemic regions, we should also consider hydatid cysts. Ultrasound and mammography are the primary imaging for evaluating a breast lump; although they can demonstrate the cystic components, they often fail to definitively identify a hydatid cyst. Because the characteristic features in ultrasonography, such as daughter cysts or the ‘water lily’ sign, may not always be present, like this case.

In areas where hydatid cyst is common, we can use serological tests, such as detecting IgG antibodies against Echinococcus too. But we should consider that their accuracy can vary, and their sensitivity and specificity are different among patients and disease stages.

By FNA, we could find a clear fluid; but it is not a reliable method for establishing a definitive diagnosis. Additionally, it has potential risks, such as accidentally rupturing the cyst and causing an allergic reaction.

Considering the risk of recurrence, complete surgical excision remains the treatment of choice. To avoid rupture and spillage of cyst contents, surgery must be performed carefully, because it can lead to recurrence or trigger severe allergic reactions. To reduce the risk of dissemination, we should start the albendazole therapy before surgery. Even after surgery, albendazole should be continued both to reduce the risk of recurrence and also to address any residual disease. Regular follow‐up imaging is essential to monitor for potential recurrence.

4. Conclusion

Although breast hydatid cysts are rare even in endemic regions, they should be considered in the differential diagnosis of any breast lump. Our case, which has an inconclusive FNA and we managed it with successful surgery, showed that imaging and cytology alone are often insufficient; careful attention to patient history, serological testing, and clinical suspicion is essential. The best approach is careful surgical removal of the cyst, combined with albendazole therapy, and then close follow‐up to prevent recurrence. In regions where the disease is more common, it's important to stay especially alert and consider this possibility in every suspicious breast lumps.

5. Discussion

Hydatid disease is endemic in regions like the Mediterranean, South America, North and East Africa, Australasia, and the Middle East, including Iran, where traditional livestock farming can cause transmission of Echinococcus granulosus [9]; [3, 11]. It predominantly affects the liver (75%) and lungs (15%), and has complications like rupture into the peritoneum or biliary system, which potentially can cause anaphylactic shock or peritonitis [1, 4, 10, 11]. Simultaneous liver‐lung involvement occurs in 5%–13% of cases, while pleural or chest wall extension is seen in 0.9%–7.4% of cases [5, 10, 14]. Isolated extra‐hepatic sites are less common, as reported in a series of 33 rare cases [12].

Breast involvement is exceptionally rare (0.27% of all hydatid cases), typically from systemic dissemination. It presents as a painless and slowly enlarging mass, which typically occurs in women between 30 and 50 years of age, with reported cases spanning 20–74 years [14]; [1, 2, 4]. This 45‐year‐old patient was from rural Gilan, which is an endemic area with sheep farming and human‐animal contact [13, 18]. She showed a recurrent cyst post‐FNA, which was aligned with diagnostic difficulties in the literature. This reflects Alamer et al.'s study [19], which was about a 46‐year‐old case that was misdiagnosed as a phyllodes tumor. Her ultrasound showed heterogeneous cystic areas and suggested hydatid preoperatively, unlike our inconclusive BI‐RADS 3 imaging. In contrast, Vega et al.'s study [20] discussed a 74‐year‐old patient with MRI's “wheel‐spoke” pattern that highlighted a variation in the utilization of advanced imaging. Geramizadeh's review [4] of Iranian cases underscores both the rarity of breast hydatid cysts and their tendency to mimic fibroadenomas or abscesses, with definitive diagnosis often established postoperatively. This is consistent with our pathology that shows laminated membranes and protoscolices.

Imaging for breast hydatid cysts is nonspecific: ultrasound may show hypoechoic lesions with “water lily” or “snowstorm” signs in types II‐III per Gharbi classification (Table 1), but our type I simple cyst lacked these and complicated the differentiation [1, 4, 15, 16, 21]. Mammography often reveals well‐defined and calcified masses [1, 2, 3, 4, 6, 16], but yet secondary infection (5% of cases) can mimic abscesses or tumors [1, 15, 16]. Botezatu et al. [7] note variable ultrasound from simple to complex echoes, while Wen et al. [22] highlight eosinophilia (absent in our 2% count) as a diagnostic clue. FNA, highlighted by Gharbi [21] for anaphylaxis risk, led to recurrence here, which underscores the avoidance in suspected hydatid.

TABLE 1.

Gharbi Classification.

CL ○ Unilocular anechoic cystic lesion ○ No internal echoes or septations ce 1 (active stage) ○ Uniformly anechoic cyst with fine internal echoes may only be visible after patient repositioning 2 ○ Internal echoes represent “hydatid sand” (fluid and protoscolices originating from a ruptured vesicle) ce 2 (active stage) ○ Cyst with internal septation ○ Septa represent walls of daughter cyst(s) described as multivesicular, rosette, or honeycomb appearance ce 3 (transitional stage) ○ The evolving appearance of daughter cyst(s) within the encompassing parent cyst ○ 3A: daughter cysts have detached laminated membranes ○ 3B: daughter cysts within a solid matrix ce 4 (inactive/degenerative) ○ Absence of daughter cysts ○ Mixed hypoechoic and hyperechoic matrix, resembling a ball of wool ce 5 (inactive/degenerative) ○ Arch‐like, thick partially or completely calcified wall. Abbreviation: CE, cystic echinococcosis; CL, cystic lesion.

Clinically, this case highlights the importance of serological testing (e.g., Echinococcus IgG) in endemic breast evaluations to reduce misdiagnosis and recurrence. It potentially reduces the morbidity in areas like Iran with thousands of annual cases [13, 18]. Surgical excision with albendazole (as in our protocol) prevents relapse. Velasco‐Tirado's meta‐analysis supports this by showing efficacy in residual disease [23]. Hygiene education can break the transmission cycles [24].

Limitations include no preoperative MRI or serology, which possibly can delay the diagnosis in our resource‐limited context, and the single‐case nature restricts generalizability. Future studies could explore serological screening in endemic breast lumps.

Figures 1 and 2 (FNA and clear fluid):

Figures 3, 4, 5, 6, 7 (Ultrasonography and Mammography):

Figures 8 and 9 (Intact laminated membrane):

Figures 10, 11, 12, 13 (Microscopic pathological findings):

Author Contributions

Sadin Zahra: supervision, validation, visualization, writing – original draft, writing – review and editing. Aghajanzadeh Manouchehr: supervision, validation, visualization, writing – original draft, writing – review and editing. Sadin Mohammadreza: supervision, validation, visualization, writing – original draft, writing – review and editing. Dadashi Arsalan: methodology, supervision, validation, visualization. Ramezani Naghi: resources, supervision, validation, visualization. Alavi Foumani Ali: funding acquisition, supervision, validation, visualization. Farzin Mohaya: validation, visualization, writing – original draft, writing – review and editing.

Funding

The authors have nothing to report.

Ethics Statement

The study was performed in accordance with the declaration of Helsinki and approved by the Ethics Committee of Gilan by the Local Ethical Committee of Arya private hospital. Iran, Rasht, Guilan, Tel: +981333759790‐9, E‐mail: info@Aryahospital.ir.

Consent

A written informed consent was obtained from the patient for the publication of this case report and any accompanying images. A copy of the consent form is available for review by the Editor‐in‐Chief of this journal.

Zahra S., Manouchehr A., Mohammadreza S., et al., “Hydatid Cyst of the Breast: A Rare Case Report and Literature Review,” Clinical Case Reports 13, no. 12 (2025): e71678, 10.1002/ccr3.71678.

Data Availability Statement

All data generated or analyzed during this study are included in this published article. No additional datasets were created or analyzed for this case report.