Primary Omental Leiomyosarcoma: Unusual Manifestation of a Rare Entity
CY Chu, MF Wong, KC Leung, P Tsui, WK Chau
Hong Kong J Radiol 2012;15:113-8
Although metastatic tumours in the greater omentum are common, primary omental neoplasms are rare. Primary omental leiomyosarcoma is a rare disease with only a limited number of reports in the literature. The lesion may cause abdominal pain, palpable mass, abdominal distension, or ascites, or may cause no symptoms. The previously reported cases are mostly large masses consisting of cystic areas surrounded by enhancing solid areas, which are the typical imaging features of leiomyosarcoma regardless of its location. We report on a patient with unusual imaging features, making preoperative diagnosis difficult. However, the imaging findings of the tumour enabled determination of the origin of the tumour in the gastrocolic ligament, which helped with surgical planning. Moreover, the lesion showed an anechoic appearance on ultrasonography, and was subsequently found to be a solid-enhancing tumour rather than a cystic lesion on computed tomographic scan. These imaging features predicted that the lesion was a homogeneous cellular tumour. The final diagnosis was made by immunohistochemical staining, which showed positive results for smooth muscle markers (smooth muscle actin and desmin). Staining for gastrointestinal stromal tumour markers, including c-kit (CD117) and CD34, were all negative. Surgical excision was performed, which is the treatment of choice for both omental leiomyosarcoma and gastrointestinal stromal tumour. The patient recovered well, with no recurrence after 18 months of follow-up. This is the first case report of leiomyosarcoma arising from the gastrocolic ligament.
中文摘要
原發性大網膜平滑肌肉瘤：一種罕見病的罕見症狀
朱志揚、黃文鳳、梁建聰、徐波、周偉強
大網膜轉移瘤很普遍，但原發性大網膜腫瘤卻很罕有。原發性大網膜平滑肌肉瘤十分罕見，文獻中 只有廖廖數個病例報告。此病變可以引致腹痛、可觸摸及腫塊、腹脹及有腹水，但亦可以無病徵。 過往的此類病例報告大部分都屬有強化實質包裹着的囊性大型腫瘤，這亦即是出現在任何位置的平 滑肌肉瘤的典型影像特徵。本文報告的病人，其非典型的影像特徵使術前診斷相當困難。但病人的 影像檢查顯示其腫瘤的原發位置為胃結腸韌帶，使醫生可作出手術計劃。此外，超聲檢查發現腫瘤 呈暗區，後CT掃瞄顯示為實質增強型病變，而不是囊性灶。這些影像結果提示這是一個均勻的多細胞性腫瘤。最後，免疫組織化學染色技術中的平滑肌分化標誌物（平滑肌肌動蛋白及結蛋白）呈陽 性結果。另一方面，胃腸道間質瘤標誌物，包括c-kit（CD117）及CD34，呈陰性。最後替病人進行 了手術切除，這是治療大網膜平滑肌肉瘤及胃腸道間質瘤的最佳方法。術後18個月，病人未有復發 跡象。這是首個源自胃結腸韌帶的平滑肌肉瘤的病例報告。