Abdominal metastasis of a parosteal osteosarcoma of the femur: an unusual cause of large-bowel obstruction.

BACKGROUND: Parosteal osteosarcoma is a rare, well-differentiated, predominantly fibro-osseous variant of osteosarcoma. It is regarded as a distinct form of osteosarcoma with better prognosis than conventional osteosarcoma. AIM: We report an unusual case of abdominal mass recurrence of parosteal osteosarcoma of the left distal femur treated eight years previously with wide resection, hip disarticulation and chemotherapy, which presented as an acute abdomen: we discuss the clinical outcomes of this rare entity. CASE PRESENTATION: We present a 54-year-old patient with low-grade parosteal osteosarcoma of the left distal femur. Left total hip disarticulation was indicated after several local relapses of the tumour following extensive resection and chemotherapy. Eight years later, he presented with an acute large bowel obstruction secondary to a compression of the large bowel by an abdominal mass. Abdominal computed tomography showed a large abdominal calcified mass with dilated large bowel loops. During laparotomy, the mass was unresectable. So, the patient underwent emergent colostomy of diversion. Biopsy of the lesion yielded grade III parosteal osteosarcoma material. The patient received adjuvant chemotherapy, but the response was poor: six months later, the patient presented with a peristomal mass and two pulmonary metastases. CONCLUSION: Abdominal recurrence of parosteal osteosarcoma of the distal femur eight years after definitive surgery is rare. This case emphasises the importance of the long-term follow-up of patients with parosteal osteosarcoma.

Mucocele of appendiceal stump--an atypical presentation and a diagnostic dilemma.

BACKGROUND: Appendiceal mucocele is a well-recognised entity that can present in a variety of clinical syndromes or can occur as an incidental surgical finding. The term mucocele is inherently imprecise and inclusive of both benign and malignant lesions. Mucocele of the appendiceal stump is a rare entity. AIM: We present a case of an appendiceal stump mucocele caused by a mucinous cystadenoma clinically presented as a giant retroperitoneal mass. Diagnosis was made postoperatively, after pathological study of the surgical sample. CASE REPORT: The case of a 54-year-old woman, with a previous appendectomy, suffering from a painful mass in the right lower quadrant of the abdomen, is reported. Imaging showed a large cystic structure at the base of the caecum. Surgery revealed a 13 x 5.5 cm retroperitoneal cystic mass, which was excised together with the appendiceal remnant. Pathological diagnosis was that of a mucocele arising from the appendiceal stump due to the development of a benign mucinous cystadenoma. The patient was discharged on the fourth post-operative day after an uneventful recovery. CONCLUSION: Mucocele of the appendiceal stump is a rare entity. In spite of extensive pre-operative investigations, preoperative diagnosis may still remain elusive and may only be made at the time of surgery.