Magnetic Resonance Imaging Verification of a Case of Sacrococcygeal Teratoma

Coccygeal tumours unveiled: a retrospective cohort analysis from a tertiary referral centre

BACKGROUND

Isolated tumours affecting the coccyx are infrequent, with only a handful of documented cases in the literature. Herein, we highlight the most extensive consecutive case series involving various isolated coccyx tumours with varied clinical presentations and imaging features.

METHODS

A retrospective search of our tertiary Orthopaedic oncology institute's oncology and Radiology database [Radiology Information System, Picture Archiving and Communication System, and Computerised Radiology Information System] for the keyword "Coccyx" and "Tumour" was performed over 15 years (between December 2007 and August 2022). Data collected was correlated with local histopathology and laboratory records. Patient demographics, clinical characteristics, and complementary imaging findings were recorded for analysis.

RESULTS

One hundred and three lesions originating in the coccyx with a mean age of 62 years (range 25-90 years) were identified. There was a male preponderance with 59 male and 44 female patients (1.3:1.0). The most typical tumour noted was chordoma. Other lesions included a dermoid cyst, a myxopapillary ependymoma, a notochordal remnant, an osteochondroma, an Ewing sarcoma, and a teratoma.

CONCLUSION

Our analysis suggests that most of the tumours involving coccyx are chordomas with a few rarely encountered benign and malignant tumours. Radiological imaging plays a vital role in characterising isolated tumours affecting the coccyx and guiding appropriate patient management.

ADVANCES IN KNOWLEDGE

This is the largest reported series of coccygeal tumours. Chordoma is the commonest coccygeal tumour. Patients with unexplained coccydynia should undergo detailed investigations, preferably with cross-sectional imaging.

Prenatal MRI diagnosis and outcomes of abdominal or sacrococcygeal teratomas and parasitic fetuses

Objective

To investigate the MRI findings of fetal abdominal or sacrococcygeal teratomas and parasitic fetuses and analyze the outcomes on the basis of follow-up assessments.

Methods

The MRI data of 60 cases of abdominal or sacrococcygeal masses were examined. The outcomes were followed up and compared with the prenatal MRI diagnoses.

Results

The 60 cases included 52 cases of sacrococcygeal teratomas and eight cases of abdominal lesions. The common types of sacrococcygeal teratomas were type I (21/52, 40.4%) and type II (20/52, 38.5%); type III sacrococcygeal teratomas were rarer (8/52, 15.4%), while type IV tumors (3/52, 5.7%) were frequently complicated with hydronephrosis. Other complications included polyhydramnios in 22 cases, placental edema in six cases, and fetal hydronephrosis in three cases (all type IV). Seven of the eight parasitic fetuses were located in the abdominal cavity, and one was located in the sacrococcygeal region. Postnatal surgery was performed in 51 cases (51/60), including 44 with teratomas and seven with parasitic fetuses. In one case with hydronephrosis, peritoneal effusion, and subcutaneous edema, treatment was discontinued after birth (1/60). Fetal induction of labor was observed in eight cases (8/60). Prenatal ultrasound yielded incorrect or ambiguous diagnoses in 11 cases, while 51 cases showed a favorable course after surgery.

Conclusions

MRI shows high accuracy in the diagnosis of fetal sacrococcygeal teratomas and parasitic fetuses. The prognosis in these cases is generally good. However, type IV sacrococcygeal teratomas are prone to fetal hydronephrosis and misdiagnosis and show a poorer prognosis.

An Aberrant Case of Sacrococcygeal Teratoma in a Female Infant Born of Twin Pregnancy

Sacrococcygeal teratoma (SCT) is an uncommon infantile tumor. It has a female preponderance with malignant variants being more common in males. These usually manifest as palpable masses over the sacral region in infancy which may or may not be associated with neural tube defects. An initial radiological investigation is warranted to analyze the extent and components of the mass to guide an approach for surgical excision. We present a classic case of an SCT in a female infant born as a twin. This mass was evaluated radiologically by X-ray and ultrasound followed by histopathological correlation. This is a case of Altman Type-I lesion and was confirmed as a mature teratoma on histopathological examination.

Primary Tumors of the Sacrum: Imaging Findings

The diagnosis of sacral neoplasms is often delayed because they tend to remain clinically silent for a long time. Imaging is useful at all stages of managing sacral bone tumors: from the detection of the neoplasm to the long-term follow-up. Radiographs are recommended as the modality of choice to begin the imaging workup of a patient with known or suspected sacral pathology. More sensitive examinations such as computerized tomography (CT), magnetic resonance (MRI), or scintigraphy are often necessary. The morphological features of the lesions on CT and MRI help to orientate the diagnosis. Although some imaging characteristics are helpful to limit the differential diagnosis, an imaging-guided biopsy is often ultimately required to establish a specific diagnosis. Imaging is of paramount importance even in the long-term follow-up in order to assess any residual tumor when surgical resection is incomplete, to assess the efficacy of adjuvant chemotherapy and radiotherapy, and to detect recurrence.