A 57-year-old woman with chronic symptoms of lumbar and gluteal pain, with aggravating symptoms in the last months, was admitted to the hospital for further evaluation. The patient was disabled by the disease. Deformity in the right gluteal area was noticed.
A 57-year-old woman had a history of primary hydatid disease of the pelvis for a long time, which led to chronic symptoms such as lumbar pain, deformity and pain in the right gluteal area. She had been disabled by the disease and underwent several surgical and antihelmintic medical treatments for the last 20 years. Over a period of a few months the pain worsened and was associated with sciatica. With aggravating symptoms the patient was admitted to the hospital for further evaluation.
Laboratory blood tests showed positive antibodies for hydatid disease. She had radiographic examinations that showed extensive bone destruction and sclerosis in the right iliac bone and sacrum (Fig. 1). The patient underwent pelvic Magnetic Resonance (MR) imaging that showed multiple soft tissue cystic masses in the right gluteal region, the right iliac and sacral bones, extending through the right sacroiliac joint. There was a replacement of the normal bone marrow by multiple single, unilocular cysts and multiseptated cystic masses forming a fistulous tract to the right gluteal area. The cystic lesions were characterised by low signal intensity on T1-weighted images and high signal intensity on STIR and T2-weighted images, owing to their inner liquid content - hydatid matrix. One lesion showed a hypointense rim on all sequences corresponding to the fibrous/calcified pericyst. (Fig. 2).
The patient underwent excision of multiple gluteal cysts with improving symptoms and was discharged. The iliac and sacral bone lesions were irresectable. Medical antihelmintic treatment was maintained before, during and after surgery.
Hydatid disease is an important health problem in some countries including Portugal. It occurs in humans as a result of faeco-oral contamination and pelvic echinococcosis is rare even in areas where echinococcosis is endemic. Hydatid cyst primarily occurs in the liver and lungs. About half of the bone involvement occurs in vertebrae. Primary hydatid cysts of the lumbar and sacral spinal canal are very rare [1]. This is an unusual presentation of recurrent pelvic hydatid disease.
Bone lesions usually show an insidious progression of the parasite into osseous tissue, leading to a diffuse, extensive, invasive process, making surgical eradication very difficult. Growth in the direction of least resistance causes cortical destruction with extension of the cyst into surrounding soft tissues as seen in this case report.
Diagnosis of hydatid cysts of the lumbosacral and pelvic areas is difficult and patients usually present with neural compression symptoms, severe weight loss, abdominal pain [2, 3], pelvic pain [4], recurrent disc disease [5], low back pain, sciatica [6], foot pain or acute cauda equina syndrome (total plegia of dorsal flexion of the left foot and perianal hypoaesthesia) [7]. The reported patient presented with sciatica caused by cyst invasion of the first right sacral anterior nerve root as shown on the MR images. She also had lumbar pain, deformity and pain in the right gluteal area caused by local invasion of soft tissues.
The diagnosis of osseous hydatidosis is based on plain radiography, computed tomography scan and MR imaging [8]. The involvement of pelvic bones made the diagnosis challenging, but findings of cysts in other tissues suggested the diagnosis of hydatid disease, as previously reported [9]. The imaging findings included single, unilocular cysts and multiseptated cysts, with “dumbbell-shaped” appearances. On MR images, one hydatid cyst wall showed the typical hypointense rim on both T1- and T2-weighted images, corresponding to the fibrous or calcified pericyst. The hydatid matrix or hydatid sand appeared hypointense on T1-weighted images and markedly hyperintense on T2-weighted images in agreement with previous findings [8]. In addition, diagnosis was aided by laboratory blood tests.
Surgical excision and additional antihelmintic medical treatment are considered the treatments of choice [5, 10]. Curative therapies are unlikely as shown in this case report. Long term survival is possible, but surgical treatment was performed at an advanced stage, when radiologic lesions were already extensive, and bone lesions were irresectable.
In conclusion, hydatid disease of the pelvis should be considered in the evaluation of cystic pelvic and sacroiliac masses, especially in areas where the disease is endemic. In addition, cystic lesions in adjacent soft tissues such as the gluteal area are highly suggestive. MR images can easily show pelvic bone cystic lesions and allow evaluation of nerve entrapment. The treatment of osseous hydatidosis may be lengthy and surgical eradication impossible, particularly in extensive disease.
Pelvic hydatid disease
1. Multiple cystic lesions are seen in the pelvic region (particularly around the sacrum and at the attachment sites of the right iliac bone and ischium), appearing as relatively well-defined or irregularly partitioned cystic shadows.
2. On MRI T1 and T2 sequences, some lesions display a clearly visible low-signal margin (suspected to be fibrotic or calcified capsule). The cyst content shows high signal on the T2 sequence, consistent with high-protein or “fluid” characteristics.
3. Some of the cystic lesions involve the vertebral body or pelvic bones, with observable bone destruction or thinning of the cortex, and local extension into the surrounding soft tissues. The left and right sides are asymmetrically affected, with more prominent involvement on the right side.
4. The right anterior sacral nerve roots are compressed or eroded by the cystic lesions, correlating with the patient’s persistent right buttock pain and sciatica.
5. A conventional pelvis AP X-ray reveals radiolucent areas of varying sizes along with bone defects, with some margins showing sclerosis or irregular changes.
Based on the imaging findings above and the patient’s history of chronic lower back and buttock pain, the following differential diagnoses are considered:
1. Echinococcosis (Hydatid disease): Commonly seen in the liver and lungs, but can also appear in the pelvic area and bones. In this case, multiple cystic lesions with bone destruction and soft tissue expansion correspond to typical “erosive” changes, consistent with hydatid disease.
2. Metastatic lesions: Tumors metastasizing to the pelvic region may show lytic lesions, though they are more common in patients with a known history of malignancy. Purely cystic manifestations are relatively less common.
3. Chronic osteomyelitis or other infectious lesions: While these can cause bone destruction and soft tissue abscesses, they often display heterogeneous signals on imaging and are typically accompanied by acute or subacute inflammatory signs (e.g., marked bone reaction, periosteal proliferation), with clinical symptoms such as fever and elevated inflammatory markers.
4. Solid bone tumors or benign cystic neoplasms: Such as aneurysmal bone cyst or giant cell tumor of bone, which can present as destructive lesions. However, their imaging features usually differ from the characteristic appearance of parasitic disease.
Taking into account the possibility that the patient comes from (or resides in) an endemic region for echinococcosis, the chronic lower back and buttock pain with recent exacerbation, and imaging findings of multiple cystic masses involving the pelvis and spine, along with supportive laboratory or serological tests, the most likely diagnosis is:
Pelvic echinococcosis (Hydatid cyst) involving the sacrum and adjacent soft tissues.
If any doubt persists, additional serological tests (such as Echinococcus antibody detection) or pathological examination (needle biopsy) can be performed to confirm the diagnosis.
1. Treatment Strategy
- Surgical Treatment: For patients with large local masses causing nerve compression or significant bone destruction, surgical decompression, lesion removal, or partial resection can relieve symptoms. However, due to deep skeletal infiltration, complete surgical cure may be limited, and comprehensive management combining other approaches is advised.
- Antiparasitic Medications: Albendazole or Mebendazole is commonly used. Pre- and post-operative administration can inhibit cyst growth and reduce recurrence risk.
- Comprehensive Therapy: If the lesions are extensive and not suitable for a single complete resection, staged surgery, interventional treatment, and long-term antiparasitic therapy can be combined.
2. Rehabilitation and Exercise Prescription
- General Principles: Because of the significant bone destruction and persistent pain, a gradual rehabilitation program under the guidance of a specialist or physical therapist is recommended. Protect the affected pelvis and spine, avoiding excessive weight-bearing or high-impact activities.
- Training Examples (FITT-VP Principle):
• Frequency: 3–5 times per week, gradually increasing up to 5 sessions per week depending on pain tolerance and patient endurance.
• Intensity: Begin with low-intensity exercises, such as seated or walker-assisted walking for 5–10 minutes, and gradually extend activity duration; avoid high loads to protect the affected areas.
• Time: Start at around 10–15 minutes per session, progressively extending to 30 minutes or longer. Multiple shorter sessions can help reduce fatigue.
• Type: Gentle lower limb strengthening exercises (e.g., seated leg raises, straight leg raises, gluteal muscle exercises), combined with low-intensity walking or hydrotherapy (like water walking) to reduce impact on the pelvis.
• Volume & Progression: Increase training frequency or duration as symptoms improve and pain subsides. Regular imaging and blood tests are recommended to evaluate whether the load or activity range can be further increased.
- Precautions:
• If significant pain, numbness, or worsening neurological symptoms occur, discontinue the activity and seek medical evaluation.
• Closely monitor any new pathological fractures or signs of hydatid lesion spread in the affected region.
• During antiparasitic treatment, keep track of liver function, complete blood count, and other laboratory indices.
Disclaimer:
This report is a reference analysis based on the patient’s provided medical history and imaging data. It cannot replace an in-person consultation or a professional doctor’s diagnostic and treatment plan. Patients should follow professional medical advice for further examinations or treatment.
Pelvic hydatid disease
