|Year : 2018 | Volume
| Issue : 10 | Page : 796-799
Low-grade myofibroblastic sarcoma of the pancreas: A case report and literature review
Long Peng1, Yi Tu2, Yong Li1, Weidong Xiao1
1 Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
2 Department of Pathology, The First Affiliated Hospital of Nanchang University, Nanchang, Jiangxi 330006, China
|Date of Web Publication||24-Sep-2018|
Department of General Surgery, The First Affiliated Hospital of Nanchang University, No. 17, Yongwai Zhengjie, Nanchang, Jiangxi 330006
Source of Support: None, Conflict of Interest: None
Low-grade myofibroblastic sarcoma (LGMS) is a malignant tumor with myofibroblastic differentiation, which frequently occurs in the oral cavity and extremities. Here, we report a case of LGMS of the pancreas in a 44-year-old female presented to our hospital with recurrent upper abdominal pain. Computed tomography revealed a low-density solid tumor at the body of the pancreas. Distal pancreatectomy combined with splenectomy was performed. LGMS of the pancreas was diagnosed by the histological features together with immunohistochemical findings. The patient received adjuvant chemotherapy after surgery and remained asymptomatic for 5 years. Previous studies and our experience suggested that surgical excision with wide margins is the reasonable treatment of LGMS and adjuvant therapy may improve its prognosis.
Keywords: Adjuvant therapy, myofibroblastic sarcoma, pancreas, pancreatectomy
|How to cite this article:|
Peng L, Tu Y, Li Y, Xiao W. Low-grade myofibroblastic sarcoma of the pancreas: A case report and literature review. J Can Res Ther 2018;14, Suppl S3:796-9
| > Introduction|| |
Low-grade myofibroblastic sarcoma (LGMS) has been reported in literature under various terms, including myofibrosarcoma, myofibroblast-rich fibrosarcoma, sarcoma of myofibroblasts, spindle-cell sarcoma showing myofibroblastic differentiation, leiomyosarcoma, and myofibroblastic variant.,, According to the World Health Organization classification of soft-tissue tumors, LGMS is categorized as a distinct tumor of atypical myofibroblasts with fibromatoses-like features, which frequently occurs in the head and neck region. LGMS is rare in the abdominal cavity. To the best of our knowledge, only one case of pancreatic LGMS has been reported in English-language literature. Here, we present a case of LGMS of the pancreas and review the literature.
| > Case Report|| |
A 44-year-old female was presented to our hospital with recurrent upper abdominal pain for 3 months. Physical examination showed moderate epigastric tenderness. Hematological and blood biochemical tests revealed no abnormalities. Serum levels of tumor markers were normal. Abdominal ultrasound showed a well-defined hypoechoic mass at the body of the pancreas. Unenhanced computed tomography (CT) showed a low-density solid tumor measuring 2.0 cm × 2.5 cm at the body of the pancreas [Figure 1]. The tumor demonstrated marginally marked enhancement on contrast-enhanced CT. A diagnosis suspicious of a solid pseudopapillary tumor of the pancreas was made before operation.
|Figure 1: Computed tomography scan shows that a low-density solid tumor at the body of pancreas|
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The patient underwent distal pancreatectomy combined with splenectomy. A solid mass at the body of the pancreas measuring 2.0 cm × 2.5 cm in diameter was obtained and used as the surgical specimen. Histological examination showed that tumor cells were fusiform, containing constricted slender nuclei with eosinophilic and fibrous cytoplasm [Figure 2]. The fusiform cells were arranged in sheet-like or storiform patterns, with a moderate cell density. Fusiform nuclei of the tumor cells had a low mitotic rate and a mild nuclear pleomorphism. Immunohistochemical staining revealed that the tumor cells were positive for smooth muscle actin (SMA), vimentin, thymidine kinase 1 [Figure 3]a,[Figure 3]b,[Figure 3]c, CD99, and CD68 and negative for S-100 [Figure 3]d, cytokeratin (CK), CD117, and CD34. The resection margins were tumor-free and none of the regional lymph nodes showed metastasis. Taking the morphological and immunohistochemical features into account, the diagnosis of pancreatic LGMS was confirmed. The patient underwent two cycles of adjuvant chemotherapy after surgery. The chemotherapy regimens consisted of a combination of ifosfamide (2.0 g/m2, day 1–3), pirarubicin (60 mg/m2, day 1), and nedaplatin (80 mg/m2, day 1–2). The patient had uneventful postoperative recovery and was well 5 years after operation.
|Figure 2: Histological examination shows that tumor cells are fusiform, containing a constricted slender nucleus with eosinophilic and fibrous cytoplasm (H and E, ×100)|
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|Figure 3: Immunohistochemistry of the tumor cells. (a) positive staining for smooth muscle actin (×100), (b) positive staining for vimentin (×100), (c) positive staining for thymidine kinase 1 (×100), (d) negative staining for S-100 (×100)|
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| > Discussion|| |
LGMS, a tumor with malignant mesenchymal features, shows myofibroblastic differentiation. According to a number of previously studies, it occurs at any age with a slight male predominance. Indolent enlargement of the mass is a typical clinical manifestation, and the patient may also develop pyrexia, chills, and leukocytosis. Imaging examinations may provide useful information, but the established diagnosis mainly depends on histological test after surgery. Histopathologically, LGMS consists of fusiform cells which are arranged in sheet-like or storiform patterns. The tumor cells have constricted slender nuclei with amphophilic or eosinophilic cytoplasm. Fusiform nuclei of the tumor cells have a low mitotic rate and a mild nuclear pleomorphism. Immunohistochemically, LGMS may be immunopositive for muscle-specific actin, α-SMA, calponin, fibronectin, and desmin but immunonegative for anaplastic lymphoma kinase (ALK) and laminin., Moreover, LGMS is not immunoreactive to S-100, CK, CD34, and EMA.
LGMS should be distinguished from leiomyosarcoma, fibrosarcoma, and inflammatory myofibroblastic tumor (IMT). Leiomyosarcoma, unlike LGMS, is typically arranged in alternating fascicles of less tapered cells which have blunt-ended nuclei with scattered paranuclear vacuoles. These cells usually express h-caldesmon, desmin, and SMA. Besides, the myofilament of leiomyosarcoma is scattered throughout the cytoplasm rather than restricted to a subplasmalemmal location as myofibroblasts. Adult-type fibrosarcoma, unlike myofibroblastic sarcoma, forms a herringbone fascicular architecture and has spindle-shaped cells with elongated, tapered nuclei and scanty cytoplasm. In addition, the cells of fibrosarcoma show no myoid differentiation on immunohistochemical staining. IMT has hypocellular fibrous areas with plenty of plasma cells and shows inhomogeneous microscopic features with an inconstantly fasciculated pattern, whereas LGMS tends to display more prominent nuclear hyperchromasia, more uniform appearance with a higher cellularity, and more widely infiltrative growth pattern than IMT. ALK gene fusions, as rearrangements of the ALK gene on chromosome 2p23, occur in 50–70% of IMTs. Furthermore, ALK reactivity has also been observed in other mesenchymal malignancies such as leiomyosarcoma, rhabdomyosarcoma, malignant fibrous histiocytoma, and Ewing's sarcoma., However, LGMS is immunonegative for ALK. Therefore, immunohistochemically positive ALK can be useful in distinguishing LGMS from other mesenchymal malignancies.
Although LGMS is considered to be a low-grade malignant tumor, it is prone to local recurrence and distant metastasis. Because of its rarity, the biological behavior and the treatment of LGMS are still unclear. Most reported cases were treated by local or wide excision with or without adjuvant therapy [Table 1]. Excision combined with adjuvant therapy may improve prognosis. Among the 23 cases of LGMS treated by excision in the review study of Yamada et al., there were five patients recurrence after excision without adjuvant treatment, but no recurrence of the three patients treated by excision with adjuvant therapy. Among the eight patients with LGMS in the abdominal cavity, all patients were treated surgically and one received additional radiotherapy. After a similar follow-up time, local recurrence occurred in four patients but no recurrence was found for the patient with additional radiotherapy. In addition, Mentzel et al. reviewed 18 cases of LGMS. After a similar follow-up time in ten patients (range from 10 to 42 months), it revealed local recurrence in two of eight cases treated by only excision and no recurrence in two cases treated by excision with adjuvant therapy. Furthermore, Khosla et al. reported a case of LGMS of the larynx which was treated with excision followed by postoperative radiotherapy and still alive 14 months after surgery.
|Table 1: Low-grade myofibroblastic sarcoma cases described in the literature|
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In the present case, the patient was treated with distal pancreatectomy combined with splenectomy, followed by two cycles of adjuvant chemotherapy. Moreover, no recurrence was found 5 years after surgery. Because LGMS is extremely rare, the standardization of its treatments including surgery, chemotherapy, and radiotherapy requires further investigations. Previous studies and our experience suggested excision combined with adjuvant therapy could improve its prognosis. Furthermore, this case could provide a helpful reference to aid in the decision-making process for the diagnosis and treatment of pancreatic LGMS.
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Conflicts of interest
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[Figure 1], [Figure 2], [Figure 3]