Angiomatous leiomyoma of the urachus: A rare entity masquerading as extraluminal gastrointestinal stromal tumor
A 45-year-old lady came with a gradually increasing painful mass in the lower abdomen for the past six months with recent onset of increased frequency of micturition. There was no history of vomiting, weight loss or alteration in the bowel habits. She was a known case of diabetes mellitus well controlled on insulin, and had undergone tubal ligation 15 years back. There was no significant family history. Her general physical examination was unremarkable. On per abdominal examination, there was tenderness in the right iliac fossa with a mobile palpable mass measuring 5 × 3 cm in size. There was no regional lymphadenopathy. Her routine biochemical and hematological investigations were within normal limits, but she was found to be HBsAg positive. Computed tomography (CT) scan of the abdomen and pelvis revealed a well-defined heterogeneous, mildly enhancing, predominantly hypodense lesion measuring 5.8 × 3.6 cm lying anterosuperior to the bladder on the right side and in close proximity to the right rectus muscle []. It was thought to be an extraluminal GIST arising from the terminal ileum. The patient was undertaken for diagnostic laparotomy. A lower midline abdominal incision was given. The abdomen was opened in layers. A fibrous band was seen extending between the anterior dome of the urinary bladder and the anterior abdominal wall at the umbilicus, which in its central portion showed a 5 × 3 cm well-circumscribed lesion. It was thought to be an urachal remnant and was excised by ligating both its ends and was sent for histopathological examination.\nThe specimen consisted of a well-encapsulated nodular mass measuring 6 × 5 × 3.5 cm. The external surface was smooth with few congested blood vessels. The cut surface was solid homogeneous with gray-white appearance []. Microscopic examination revealed a well-circumscribed smooth muscle tumor comprising of spindle-shaped cells arranged in interlacing fascicles and whorls. The cells had long slender bipolar cytoplasmic processes and cigar-shaped nucleus. The stroma showed myxoid and hyaline change at places. Numerous thick-walled blood vessels were evident with their inner muscle layer arranged circumferentially and outer layer blending with the less well-ordered smooth muscle of the tumor []. Immunohistochemically, the tumor cells were positive for smooth muscle actin (SMA) and desmin; and negative for CD117 (to differentiate from GIST). The vessels showed immunoreactivity for CD34 []. The patient is symptom free with no residual disease or recurrence after a follow-up period of 6 months.