A small leiomyosarcoma of the pancreas treated by local excision

Abstract

Background

Leiomyosarcoma of the pancreas is a very rare tumour; only 33 cases have been reported in the English literature. Because these tumours tend to be large and locally advanced, extended resection such as pancreatoduodenectomy or distal pancreatectomy has been advocated.

Case outline

A 25-year-old woman with left-sided back pain had a small low-density lesion (2×2 cm) in the pancreatic body on computed tomography (CT). The tumour was initially diagnosed as a pseudocyst and was managed conservatively. A repeat CT scan 10 months later showed an increase in the size of the lesion (3.5×3.5 cm) with contrast enhancement of a high-density area. The diagnosis was therefore changed to papillary-cystic neoplasm. At laparotomy, the tumour seemed to be arising from the mid-body of the pancreas with no invasion into surrounding organs. Local excision of the tumour was performed. Pathological examination revealed a leiomyosarcoma of the pancreas.

Discussion

Complete surgical resection offers the only potential chance of cure for patients with leiomyosarcoma of the pancreas.The lack of evidence of recurrence at three-and-a-half years suggests that the less invasive surgical procedure in the present case has been curative. Careful and intraoperative exploration was important to determine the best surgical procedure.

Introduction

Pancreatic leiomyosarcoma is a rare tumour, with only 33 previous case reports in the English literature. Baylor and Berg gave an incidence of 0.1% among 5057 pancreatic malignant tumours ¹. We report a case of pancreatic leiomyosarcoma in a young woman who underwent surgical resection.

Case Report

A 25-year-old woman presented with left-sided back pain and left-sided epigastric tenderness in May 1998. Serum amylase and other laboratory data were nomal. CT scan revealed a 2 cm low-density lesion located in the body of the pancreas (Figure 1). The initial diagnosis was of a pseudocyst developing in an area of localised pancreatitis, and it was decided to observe the tumour. In March 1999, 10 months after the initial investigation, CT scan and ultrasonogram (US) showed an increase in the size of the lesion. In the arterial phase of the CT scan, a mass measuring 3.5×3.5 cm was shown to be heterogeneously enhanced by contrast medium (Figure 2). No masses were seen in the liver. Abdominal angiography showed an approximately 4 cm tumour stain arising from the dorsal pancreatic artery. There was no encasement of vessels (Figure 3). These findings led to a revised diagnosis of papillary-cystic neoplasm.

Figure 1. .

Contrast-enhanced axial CT demonstrating a 2 cm low-density pancreatic lesion.

Figure 2. .

CT scan showing growth of the tumour, which is heterogeneously enhanced by contrast medium.

Figure 3. .

Abdominal angiography shows an approximately 4 cm tumour stain arising from the dorsal pancreatic artery.

Laparotomy was performed in June 1999. At exploration, the tumour was seen to arise from the mid-body of the pancreas with no invasion into the surrounding organs. Local excision of the tumour was performed. The surgical margins were macroscopically negative.

The size of the tumour was 3.5 cm. A sagittal section showed a yellowish–white tumour with spotty necrosis (Figure 4). The tumour was examined histologically as well as immunohistochemically. Surgical margin was also histologically negative. It had a spindle cell pattern arranged in interlacing fascicles (Figure 5). On the basis of the degree of cellular atypia and the mitotic count (20 per high power field), malignancy was strongly suspected. Immunohistochemical studies revealed positivity for smooth muscle actin and desmin and negativity for S-100 protein. The pathological diagnosis was thus confirmed to be leiomyosarcoma.

Figure 4. .

Sagittal section of the tumour.

Figure 5. .

Photomicrograph showing the tumour comprises spindle-shaped cells with eosinophilic cytoplasm in an interlacing arrangement (haematoxylin and eosin stain, ×200).

The patient remained well with no radiological sign of recurrence three-and-a-half years after the operation.

Discussion

Pancreatic leiomyosarcoma is extremely rare. Details of the 34 reported cases are shown in Table 1. Some authors are doubtful about a pancreatic origin because it is such an unusual site for stromal tumours ²,³. Leiomyosarcomas originating from other organs such as the stomach, duodenum, and retroperitoneal organs often invade the pancreas, simulating a primary tumour of the pancreas. The diagnosis of pancreatic leiomyosarcoma is confirmed by ruling out a tumour arising from other surrounding organs. In the present case, the tumour was predominantly located in the mid-body of pancreas, and the CT scan, US and operative findings showed no evidence of tumour invasion into the adjacent organs. Abdominal angiography revealed that the tumour was supplied by the dorsal pancreatic artery. The pancreatic origin of leiomyosarcoma was thus confirmed.

Table 1. Thirty-four reported cases of leiomyosarcoma of the pancreas (including the present case).

Case no.	Author	Year	Age (y)	Sex	Site and Size	Treatment	Clinical outcome	Metastasis
1	Ross 5	1951	80	M	whole pancreas, LM	autopsy case	–	widespread
2	Berman 6	1956	47	M	head, 5.5 cm	pancreatoduodenectomy	alive, 12 months	none
3	Feinberg 4	1957	14	M	head, 11 cm	pancreatoduodenectomy	–	none
4	Becker 7	1965	–	–	–	–	–	–
5–9	Baylor 1	1973	–	M:3, F:2	–	–	–	–
10, 11	Heerden 8	1981	–	–	–	pancreatoduodenectomy	–	–
12	Ishikawa 9	1981	44	M	head, 8 cm	pancreatoduodenectomy	died, 4 years	liver
13	Murata 10	1990	55	M	tail: 10 cm, head: 5 cm	distal pancreatectomy	_	none
14	Lakhoo 11	1991	68	M	body, 17 cm	distal pancreatectomy	alive, 32 months	none
15	Takashima 12	1991	68	M	head, 10 cm	pancreatoduodenectomy	alive, 18 months	Liver
16	De Alava 13	1993	71	M	body, 3.6 cm	distal pancreatectomy	–	none
17	Russ 14	1993	67	M	body–tail, 10 cm	non-resectable	–	liver, spleen, LN
18	Sato 15	1994	53	F	tail, 25 cm	distal pancreatectomy	–	–
19	Ishii 16	1994	66	M	tail, 4.5 cm	non-resectable	alive, 34 months	widespread
20	Aranha 17	1995	45	F	body, 3 cm	distal pancreatectomy	died, 9 months	liver
21	Hamamoto 18	1995	55	F	tail, 5.5 cm	distal pancreatectomy	died, 15 months	lymph nodes
21	Shimizu 19	1997	49	F	head, 15 cm	non-resectable	died, 3 months	widespread
22	Chawla 20	1998	45	F	head, 9.2 cm	non-resectable	alive, 19 months	liver, Lung
23	Zalatnai 21	1998	57	M	head, 6 cm	non-resectable	died, 7 months	liver
24	Paciorek 22	1998	63	F	body, 2 cm	distal pancreatectomy	–	–
25	Machado 23	2000	52	M	head, 7.5 cm	pancreatoduodenectomy	alive, 24 months	none–
26	Srivastava 24	2000	49	M	body–tail, LM	distal pancreatectomy	–	–
27	Srivastava	2000	38	M	body–tail, LM	non-resectable	died, 3 months	peritoneum
28	Srivastava	2000	45	M	head, LM	non-resectable	–	–
29	Srivastava	2000	41	M	head, 3.5 cm	pancreatoduodenectomy	died, 6 months	liver
30	Ferlan Marolt 25	2000	57	F	body, 12 cm	distal pancreatectomy	died, 5 days	none
31	Nesi 26	2001	76	M	tail, 8 cm	distal pancreatectomy	died, 12 months	none
32	Deveaux 27	2001	44	F	head, 7 cm	pancreatoduodenectomy	alive, 4 years	none
33	Aihara	2001	25	F	body, 3.5 cm	local resection	alive, 24 months	none

LM = large mass, LN = lymph node; – =no information available.

Feinberg et al. stated that these tumours arise from the wall of the blood vessels of the pancreas or from the pancreatic duct itself ⁴. In our case, the tumour was microscopically recognised as arising from the edge of the pancreatic tissue, but there were no definitive findings to determine its origin with clarity.

Pancreatic leiomyosarcoma is reported to be a highly aggressive malignancy, which spreads in a similar manner to gastric leiomyosarcoma, i.e. by adjacent organ invasion, haematogenous spread, and lymph node metastasis. As shown in Table 1, these tumours are large at the time of diagnosis and are usually found at an advanced stage. Therefore, extended resection such as pancreatoduodenectomy or distal pancreatectomy has been advocated. In our case, however, the tumours were small, and preoperative imaging revealed no regional or distant metastasis. Furthermore, intraoperative exploration revealed an apparent margin of the tumour, which was therefore selected for local excision; both macroscopic and microscopic margins were negative. Although histopathological examination revealed a relatively high mitotic count, the patient has shown no sign of recurrence during a follow-up period of three-and-a-half years.

Future innovations in diagnostic technology may allow earlier diagnosis of leiomyosarcoma of the pancreas. Small lesions may be suitable for local exision, as is the present case, but thorough preoperative imaging and careful operative exploration are needed to justify such an approach.