Leiomyosarcoma of the transverse colon with lymph node metastasis and malignant transformation: a case report

Primary leiomyosarcoma of the colon: a report of two cases and review of literature

Introduction

Primary leiomyosarcoma (LMS) of the colon is a rare neoplasm and constitutes less than 0.1% of all colon malignancies. These tumors are more aggressive and have poorer prognoses than other gastrointestinal tumors, including gastrointestinal stromal tumors (GIST) or adenocarcinomas. The authors herein report two cases and review the literature to highlight the epidemiology, diagnosis, treatment and prognosis of this uncommon malignancy.

Case report

The authors reported two very rare cases of LMS of left colon, which referred to our institution with symptoms of abdominal pain. After the initial investigations, patients were diagnosed with primary colonic leiomyosarcoma that underwent laparotomy. In both cases pathological examination revealed a spindle cell tumor growing circumferentially and transmurally in the colon. Final immunohistochemistry were positive with SMA, CK and desmin without the expression of GIST markers (CD117, CD34 and DOG1) that confirmed leiomyosarcoma. One patient was diagnosed with diffused peritoneal metastasis at 6 months postoperatively and he died after 2 months of paliative care, another one is still on active surveillance.

Discussion

LMS of the colon is a really rare entity and is only presented in clinical case reports. LMS has non-specific symptoms and is commonly diagnosed when it reaches a large size. Surgery is a mainstay treatment option. Nowadays, there is no clear evidence for the effectiveness of chemotherapy and radiation therapy.

Conclusion

LMS is a rare neoplasm of colon. For the time being, there is no guidelines for treatment, but surgery still plays a fundamental role.

High grade leiomyosarcoma of the transverse colon with positive lymph node metastasis: to treat or not to treat with adjuvant radiation therapy?

Intra-abdominal leiomyosarcomas (LMSs) are aggressive malignant tumours arising from smooth muscle cells. These neoplasms are extremely rare and account for 10%-20% of primary soft tissue sarcomas and approximately 0.1% of all colorectal malignancies. Intra-abdominal LMS has a very poor prognosis with an estimated 5-year survival rate between 20% and 50% and the size of the tumour being the main determinant of prognosis. Treatment is further complicated by different anatomic variants with differing clinical behaviours impacting prognosis. Newer techniques in radiation treatment such as intensity-modulated, intraoperative electron and proton beam radiotherapies allow for cases with high probability of local recurrence or likelihood of residual microscopic disease after surgical resection to be treated with precise radiation doses to the targeted tumour volume. We present a case of high grade LMS of the distal transverse colon with positive lymph node metastasis treated by surgical excision followed by adjuvant radiotherapy and discuss the current role of radiotherapy.

Giant leiomyosarcoma of the transverse colon

Leiomyosarcoma (LMS) of the colon accounts for <1% of all colorectal malignancies. Our patient was a 72-year-old man with a history of aortic valvular disorder and congestive heart failure, who presented with an abdominal mass and no constitutional symptoms. The CT scan finding suggested a large tumour with both solid and cystic components. Intraoperatively, a portion of the involved colon was resected along with the tumour. Microscopically, the tumour was found to invade the muscularis propria layer of the transverse colon. The final diagnosis was LMS, FNCLCC grade 2 of 3 based on the histology and immunochemistry.

The first case of gastric leiomyosarcoma developed through malignant transformation of leiomyoma

Malignant transformation of gastric leiomyoma has not been reported, and therefore it is considered to have virtually no malignant potential. We report a case of gastric leiomyosarcoma arising from leiomyoma. The patient is a 72-year-old man with a submucosal mass measuring 20 mm in diameter, which was incidentally identified by an endoscopic surveillance. A biopsy suggested a diagnosis of leiomyosarcoma, and local excision was performed. Pathological examination revealed that the tumor was composed of two distinct components: typical leiomyoma-like area in the periphery and leiomyosarcoma component exhibiting higher cellularity, prominent nuclear atypia, necrosis, and increased mitosis. Immunohistochemically, in the latter, p53 overexpression, increased Ki-67 labeling index, and attenuated expression of smooth muscle markers were noted. This is the first report to demonstrate the presence of leiomyoma-leiomyosarcoma sequence in the stomach that is well recognized in the uterus. Our observation highlights the potential occurrence of malignant transformation of gastrointestinal leiomyoma.