Presentation
Lower abdominal and back pain. Palpable mass in pelvic region.
Patient Data
A well-circumscribed encapsulated abnormal signal mass lesion measuring 9.6 x 3.7 x 5.1 cm (AP x CC x T) is noted in the presacral region anterior to the L5-S3 segments, closely related to the sacral plexus. It demonstrates intermediate to low signal on T1WI, heterogeneously high signal on T2 fat sat and diffusion restriction on DWI/ADC. Post-contrast images show heterogeneous enhancement of this lesion.
Histopathology Report:
Macroscopic Findings:
Specimen received in formalin consists of single unoriented lobular shape piece of tissue measuring 8.0 x 3.0 x 2.0 cm. The overlying capsule is intact. Serial slicing reveals a yellowish lesion (9.0 x 3.0 x 3.0 cm).This lesion is touching nearest inked resection margin. Representative sections are taken in six blocks as A1-6.
Microscopic Findings:
Histological examination of sections show a neoplasm arranged in hypo and hypercellular areas.
Individual neoplastic cells are spindle shaped and have elongated serpentine nuclei and moderate amount of eosinophilic cytoplasm. Few hyalinized blood vessels are noted in the background. Verocay bodies are evident. Few aggregates of lymphoid cells are also seen. No atypia, increased mitotic activity or necrosis is seen. There is no evidence of malignancy.
Diagnosis:
Presacral retroperitoneal mass:
- Schwannoma
- No evidence of malignancy is seen
Case Discussion
In this patient, a preliminary diagnosis of pelvic endometrioma was made on the basis of ultrasound findings and she was referred for an MRI. The patient went on for surgery and followed by excision biopsy of the lesion. The histopathology report (see above) found the mass to be a schwannoma.
Schwannomas, although a common intradural extramedullary tumor of the spine, is found rarely in the sacral region and is often incidental.