Leiomyoblastoma of the stomach.
AK Sarda, Arunabh
Dept of Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi., India
A K Sarda
Dept of Surgery, All India Institute of Medical Sciences, Ansari Nagar, New Delhi.
A case of gastric leiomyoblastoma in a 37 year old male is presented. The patient presented with 3 episodes of melaena requiring blood transfusion on one occasion. There was no associated haematemesis, abdominal pain, obstruction or a palpable lump. The tumor was sessile and completely intraluminal with superficial ulceration displaying distinctive histologic features. Seven years after partial gastrectomy the patient has remained asymptomatic.
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Sarda A K, Arunabh. Leiomyoblastoma of the stomach. J Postgrad Med 1992;38:152-3
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Sarda A K, Arunabh. Leiomyoblastoma of the stomach. J Postgrad Med [serial online] 1992 [cited 2014 Aug 30 ];38:152-3
Available from: http://www.jpgmonline.com/text.asp?1992/38/3/152/685
Leiomyoblastoma is an uncommon smooth muscle tumour of the stomach. It was first reported in 1960 by Martin et al who described six cases of an unusual type of smooth muscle tumour characterized by unusual round cells with perinuclear vacuolization. Stout studied 69 cases with similar histology and concluded that these tumors arise from a distinctive cell, the leiomyoblast. He proposed the term leiomyoblastoma to distinguish this new entity from the common tumours of the smooth muscle. These uncommon tumours rarely metastasize although malignant variants have been described .The stomach accounts for the primary site in 93% of the cases, while the extragastric primary sites include the ileum, jejunum, duodenum, colon, rectum, uterus, vulva and soft tissues.
A male patient, aged 37 years, was admitted with a past history of three episodes of melaena (three to four formed tarry stools per day) lasting from 7-30 days. There was a history of one small vomit of coffee coloured material during the first episode when a barium meal study revealed a duoddnal ulcer. Although the patient was detected to be anaemic during all the three episodes of melaena, the patient required transfusion of two units (350 ml each) of blood only during the second episode. On all occasions, the patient responded to antacid and haematinic therapy. On admission in our unit, examination of the patient revealed pallor but was otherwise unrewarding with no localizing abdominal signs. The haemoglobin was 8.2 gm/dl and the other blood chemistry was essentially normal. Stool tested positive for occult blood. The chest skiagram was normal. Barium meal study revealed a well- defined, smooth filling defect in the prepyloric region with a small ulcer in the centre classically described for leiomyomas of stomach; the gastric mucosa and the duodenal cap were found to be normal. Gastroscopy showed a smooth surfaced mass in the prepyloric area. Laparotomy was performed. A mass was felt in the prepyloric areas of the stomach; there was no perigastric extension, enlarged draining lymph nodes, or any secondaries in the liver. There was no evidence of peptic ulcer. A partial gastrectomy was performed.
Grossly, a 2.5 cm, firm, sessile, intraluminal tumour was seen with a central ulcer crater. Histologically, most of the cells were round or polygonal having eosinophilic, faintly granular cytoplasm and were arranged in regular branching fashion. There was a typical perinuclear vacuolization, with oval nuclei showing mild pleomorphism and occasional mitotic figures. A diagnosis of leiomyoblastoma was made.
The patient has remained asymptomatic for 7 yrs post-operatively.
The natural history of leiomyoblastomas (synepitheijoid ieiomyoma, bizarre smooth muscle tumour) appears to be different from the other types of smooth muscle gastric tumours. More than 85% of these tumours occur in patients over 40 years of age with a predilection of men over women in the ration of 2:1, More than 50% of the tumours present with symptoms of haemorrhage, followed by epigastric pain and discomfort, palpable mass, and loss of weight,. Pyloric antrum is the most common site of occurrence, followed by the body of the stomach. The size of the tumour is variable (0.5 to 20 cm); the largest reported tumour measured 35 x 20 x 8 cm . The lesion is usually single but multiple lesions have been reported. Gastroscopy may exclude a carcinoma or an ulcer but the endoscopic appearance of leiomyoblastomas is in no way different from other intramural tumours.
Radiologically, leiomyoblastomas are markedly similar to leiomyomas and lelomyosarcomas, the only differentiating feature being the marked predilection of leiomyoblastomas for the gastric antrum. Approximately 75% of leiomyoblastomas are completely or predominantly antral, whereas 70% of all other mesenchymal tumours of the stomach are situated in the body and fundus. About 85% of leiomyoblastomas are intramural with more than 50% showing surface ulceration. About 4% of these tumours may be intraluminal or less commonly exogastric; multiple, simultaneous tumours, target or "bull's eye" ulceration are other rare radiological findings. Histologic features are highly characteristic,. The majority of the cells are round or polyonal having eosinophilic cytoplasm and arranged in regular branches or irregular strings. The most important feature is the presence of a clear zone (vacuolization) completely or partially surrounding the nucleus and showing a negative staining reaction for mucus, glycogen and lipids. Criteria for diagnosing malignancy are similar to all spindle connective tissue tumours and can be suspected when the number of mitotic figures are 10/HPF and there is evidence of necrosis. However, the reliability of these parameters in predicting tumour behaviour is limited. The true character of the tumour can only be found by the presence of metastasis either to the lymph nodes or the liver or by its subsequent behaviour in recurring locally or metastasizing. Thus, careful followup of these tumours, showing no significant differentiating histologic features between benign and malignant lesions, is mandatory since their subsequent behaviour is difficult to predict. The vast majority run a benign course, however, since the tumour does not have a true capsule and is locally invasive, partial gastrectomy is the treatment of choice.
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