CECT Abdomen-Pelvis for reporting. Patient presenting with pelvic lump, pain in abdomen, Positive Urine pregnancy test & a Pelvic mass on USG.

Imaging findings :

  • A large, 15×15 cm sized heterogeneously enhancing, solid-cystic pelvic mass lesion.
  • Mild ascites & mild omental thickening. Neither ovary was seen separately.
  • Fat planes between the lesion & adjacent Pelvic structures maintained.
  • No significant abdominal-pelvic lymphadenopathy.

Radiological Diagnosis : Ovarian Neoplasm (most likely Germ cell tumor- considering patient’s age) with peritoneal spread.

Discussion :

Germ cell tumors are the most common ovarian masses in children & adolescents.

Ovarian malignant germ cell tumors (OMGCTs) tend to be large at the time of diagnosis and progress rapidly. They typically manifest in adolescence with abdominal pain and an abdominal mass. About 10% of patients present with an acute abdomen resulting from torsion, hemorrhage, or tumor rupture (which is more common with yolk sac tumors or mixed germ cell tumors). Less common symptoms include abdominal distention, fever, and vaginal bleeding. Duration of symptoms is usually short, with a median of 2–4 weeks.

Endocrinal manifestations resulting from hormone production by tumor cells are relatively uncommon & include menstrual irregularities, isosexual precocity, carcinoid syndrome & false positive Urine pregnancy test.

Atypical findings in this case :

  • Positive urine pregnancy test.
  • Peritoneal spread without evidence of lymphatic dissemination- unusual for Germ cell tumors.

1Axial section of Pelvis during the venous post-contrast phase showing the heterogenously enhancing Pelvic mass

2Axial section of Pelvis during the venous post-contrast phase showing the heterogenously enhancing Pelvic mass.

3Coronal section further demonstrating the lesion & ascites.

4Axial section of Abdomen showing Ascites & Omental thickening.

Introduction:

Osteochondromas are considered a chondroid neoplasm and account for 10-15% of all bone tumours and ~35% of all benign bone tumours.

Osteochondromas are part of the growth plate which separates and continues to grow independently, without an associated epiphysis, usually away from the nearby joint. The medullary cavity is continuous with the parent bone, and hyaline cartilage caps them.

Radiographic features

Plain radiograph

  • An osteochondroma can be either sessile or pedunculated.
  • Seen in the metaphyseal region typically projecting away from the epiphysis.
  • The cartilage cap may be thin and difficult to identify, or thick with rings and arcs calcificationand irregular subchondral bone.
  • New cortical irregularity or continued growth after skeletal maturity has been reached, as well as frankly aggressive features (e.g. bony destruction, large soft tissue component, metastases) are all indicators of malignant transformation.
  • Skeletal survey is indicated to rule out multiple osteochondromas which can be part of Hereditary multiple exostoses(HME) or Trevor disease.

CT

  • CT is better able to demonstrate medullary continuity and the cartilage cap.

Ultrasound

  • Ultrasound shows the cartilage cap as a hypoechoic region bounded by bone on its deep surface and muscle/fat superficially.

MRI

  • MRI is the best imaging modality to assess cartilage thickness (and thus assessing for malignant transformation), the presence of oedema in bone or adjacent soft tissues.
  • The cartilage cap of osteochondromas appears as intermediate to low signal on T1 and high signal on T2 weighted images.
  • A cartilage cap more than 1.5 cm in thickness is suspicious for malignant degeneration.
  • With intravenous gadolinium administration, enhancement of benign lesions is normally seen in the tissue that covers the cartilaginous cap which is fibrovascular in nature, however, the cartilaginous cap itself should not enhance.