A case of primary gastric undifferentiated high-grade pleomorphic sarcoma diagnosed with chief complaint of fever: a case report and literature review

Background Undifferentiated high-grade pleomorphic sarcoma in gastrointestinal tract is extremely rare, and its prognosis is poor. Case presentation An 82-year-old man visited a previous hospital complaining of fever, general fatigue, and shaking chill, for which he received antibiotics therapy. As the fever continued, he was referred to our hospital, where computed tomography and upper gastrointestinal endoscopy showed a 6-cm gastric tumor. A preoperative biopsy was consistent with a malignant mesenchymal tumor, but could not provide a definitive pathological diagnosis nor prove a cause-and-effect relationship between the chief complaint and the gastric tumor. The gastric tumor had grown to 8 cm in diameter within a month so we performed a partial gastrectomy. The pathological postoperative diagnosis was undifferentiated high-grade pleomorphic sarcoma that produced granulocyte colony-stimulating factor. The patient’s fever quickly improved, and he showed a good postoperative course. Conclusions We herein report a case of rapidly growing, undifferentiated, high-grade pleomorphic gastric sarcoma, which presented as a chief complaint of fever.


Background
Undifferentiated high-grade pleomorphic sarcoma (UPS) is a soft-tissue tumor usually found in the limbs and in the retroperitoneum. Its prognosis is poor. Occurrence in gastrointestinal tract is extremely rare. Here, we report a rare case of rapidly growing gastric UPS associated with a persistent fever and discuss the relevant literature.

Case presentation
An 82-year-old man presented at a nearby hospital with fever, general fatigue, and shaking chill in July 2015. Although he was treated with antibiotics for his high level of c-reactive protein (CRP), his 38-39°C fever remained. He was therefore referred to our hospital. When first examined, his body temperature was 38.4°C but had normal blood pressure and pulse rate. No abnormal palpable mass was reported. His blood examination findings showed high inflammatory reaction, slightly low coagulability, and mildly activated fibrinolysis. However, we observed no immunoglobulin or specific antibody that could be considered the cause of his fever (Table 1). Abdominal computed tomography (CT) in early August showed a 6-cm tumor in the stomach ( Fig. 1a) with an estimated volume of 18.07 ml. Neither other tumor nor abscess was observed. Gastrointestinal endoscopy (GIE) in early August showed a 6-cm pedunculated oval tumor on the upper part of the greater gastric curvature (Fig. 2). We also found a nearby 2-cm sub-pedunculated oval tumor. They were elastic-hard, with a smooth surface and a sparse ductal structure.
Biopsy specimen showed the proliferation of atypical cells having pleomorphic or bizarre nuclei. Immunohistochemically, some atypical cells were positive for c-kit, alpha SMA, HHF-35, and calponin, but negative for EMA, cytokeratin (CK) CAM5.2, DOG-1, CD34, caldesmon, and desmin. Although these findings were consistent with malignant mesenchymal tumors, they did not confirm the pathological diagnosis. Upper gastrointestinal fluoroscopy in early August showed a 7-cm, multinodular sub-pedunculated raised lesions with a 12-mm attachment on the upper part of the greater gastric curvature (Fig. 3). The 2-cm tumor observed in the GIE was not visualized. In early September, a CT showed that the gastric tumor had expanded to 8 cm in diameter within the month, with the volume increased to 53.50 ml (Fig. 1b). The patient's preoperative fever of 38°C or higher, which was improved to 36°C by taking acetaminophen, occurred once or twice every day. But, he had no symptoms such as abdominal pain and digestive tract obstruction.
We considered that surgery to patients with fever was dangerous, and we could not preoperatively confirm pathological diagnosis of the tumor or its cause-andeffect relationship to the main complaints. But, we finally chose to treat the tumor surgically because we found no lesion that could have caused the fever, and we were concerned that, if delayed, local resection of such a rapidly growing tumor would become impossible.
In mid-September, we performed a partial gastrectomy. We used laparoscopic assistance to disconnect the  Although the patient had a 38°C fever twice on 1-2 postoperative days (POD), no fever or other complications were observed thereafter. He began taking meals on 5POD, and he was discharged with satisfactory progress on 12POD. Positron emission tomography (PET)/ CT examination on 1 month after surgery showed accumulated fluoro-2-deoxy-D-glucose at the wound, but no other abnormal accumulation.

Discussion
Malignant fibrous histiocytoma (MFH) has been classified into three subtypes: pleomorphic, inflammatory, and giant cell. By the World Health Organization (WHO) classification of bone and soft-tissue tumors of 2002, pleomorphic-type MFH was defined as a synonym for UPS [1]. Typically, UPS forms a large, rapidly growing solid mass and is histologically characterized by pleomorphic tumor cells in storiform patterns. UPS does not tend to show clear differentiation and has no specific immunohistological marker [1,2]. Although UPS was defined in 2002, its epidemiology and prognosis has obscured because of its rarity. In reports of MFH, it commonly occurs in men and those older than 40 years, with a frequency of 1-2 cases per 100,000 people [3].MFH has been reported in limbs (68%), abdominal cavity/retroperitoneum (16%), trunk (9%), head and neck (3%), or gastrointestinal tract (4%). Its prognosis is poor, with a repoted 2-year survival rate of 60%, and a 5-year survival rate of 47% [3].
Primary gastric UPS or MFH is quite rare. Saito et al. reported 16 case reports of primary UPS or MFH of stomach, including one they reported and 14 found in PubMed using the keywords "undifferentiated pleomorphic sarcoma" and "malignant fibrous histiocytoma" a b c d e f during 1984-2011 [4][5][6][7][8][9][10][11][12][13][14][15][16]. The data of 16 cases and this case are summarized in Table 2. The average age was about 61 years old (range: 17-82 years old). Average diameter was 6.7 cm (range: 1-15 cm). Seven of the 16 patients showed invasion or metastasis and had died by the time they were reported. Only 4 of the 16 patients were 2-year survivors at the time they were reported. No 5-year survivors were yet reported. UPS is considered to have worse prognosis than other forms of MFH. In addition, there has been no report about gastric UPS producing G-CSF. According to the National Comprehensive Cancer Network (NCCN) Soft Tissue Sarcoma Guidelines, surgical resection with sufficient margin is the first-choice treatment for UPS. Amputation is required for tumors in limbs, so various surgical methods have been used with the aim of preserving function [17]. The first choice for resectable sarcomas in the inner trunk is considered to be en bloc excisions with ≥1-cm margins. Additional resection is recommended for margins narrower than 1 cm. As lymphatic metastasis is rare, systematic lymph node resection is not required. If hepatic metastases or infiltrations to nearby organs are resectable, their complete resection is desirable. Chemotherapy, radiation therapy, or hyperthermia have been used for unresectable tumors. The combination of cisplatin, ifosfamide, and adriamycin for reducing metastasis has been reported [18]. However, chemotherapy, radiation therapy, and hyperthermia have not led to satisfactory results [19,20].
At first we suspected that infection or autoimmune diseases could have caused the fever and high CRP level; we had doubts about their association with the gastric tumor. However, as the fever and CRP level dramatically improved after the surgery, the gastric tumors were clearly related to the main complaints. There are reports about cases of UPS and MFH presenting initially with fever [21][22][23], and reports about cases of MFH producing actively cytokines such as G-CSF [24][25][26][27]. But. this is the first report about gastric UPS with fever and rapid growth due to producing G-CSF. G-CSF is thought to cause paraneoplastic syndrome such as fever or increased CRP, and cytokines such as G-CSF have been suggested as markers for UPS. In this case, we should reflect that treatment was delayed because we could not understand that these symptoms could be a clue to the diagnosis.

Conclusions
We found a rare case of gastric UPS. As UPS is a rapidly growing, frequently recurring tumor, its prognosis is poor. Patients require strict postoperative observation.