Solitary Fibrous tumor arising from the Omentum

A 60-year old man presented with a one week history of intermittent periumbilical pain. He had weight loss of half a stone over 6 weeks and abdominal distension for 2 weeks, there was no other systemic complaint. General examination revealed bilateral Dupuytren`s contracture and grade 4 finger clubbing. Abdominal palpation revealed a very large non tender mass. The Liver and spleen were difficult to assess because of the size of the mass. Rectal examination was normal. An abdominal Ultrasound showed a central abdominal mass of mixed echogenicity. CT scan showed a large lobulated mass with overlying serpinginous vessels with a clear plane posteriorly separating it from the retro-peritoneum. Liver, spleen and pancreas showed no abnormality. CT scan of the chest showed no abnormality. Core biopsy under ultrasound guidance revealed features consistent with a solitary fibrous tumor, haemangiopericytoma or angiosarcoma. The patient underwent a midline laparotomy. The huge mass was attached to the greater omentum by a pedicle with minimal adhesions to the lateral peritoneum. It was excised compeletly. The post-operative course was uneventful. Gross pathological findings macroscopically revealed the mass measuring 24x19x10 cm, weighing 3870 grams and on section it was a fleshy lobulated tumour with a few cystic areas. There was some attenuated fat on part of the surface. Histologically, the architecture was pattern-less with prominent stromal hyalinization, varying cellularity (mainly spindle and ovoid cells) and branching (haemangiopericytoma-like) vessels.