Case presentation
A 53-year-old man with a history of MLS in the left thigh was treated with wide excision at local hospital. No metastases were found anywhere in the patient’s body at that time, and no adjuvant therapy was given after surgery. 2 years later, the patient found an ”egg”-like swelling above the knee on the left lower extremity, without pain or fever. After tumor resection, histological findings of the resected specimen revealed large number of hyperplastic small vessels in a fibro-mucinous background, the tumor cells are diffusely distributed in the mesenchyme, dense, asteroidal or irregular in shape, with abundant cytoplasm and red staining, a round cell component of 15%, nuclear splitting about 7/10 HPF. Adjuvant chemotherapy with two cycles of epirubicin (60 mg/m2/d on days 1-2) and ifosfamide (30 mg/m2/d, on days 1-3), mesna (18 mg/m2 on hours 0, 4, 8) and apatinib capsules (250 mg) was administered. This regimen was repeated every 3 weeks. During the treatment, the patient’s condition was stable, and received adjuvant radiotherapy at the same time. 2 months after the second surgery the patient developed chest tightness and wheezing and lower limb edema, he could not lie flat at night. Physical examination reveals an enlarged cloudy heart and audible pericardial fricative sounds. A mass measuring approximately 5.0 cm × 4.0 cm was palpable in the left groin and a mass measuring approximately 1.8 cm × 1.5 cm was palpable in the left popliteal fossa, which were tough, painless and fixed. The tumor markers revealed that tumor associated antigen 125 level was increased to 192.20 U/mL (normal range 0.01-35 U/ml).
Imaging examinations: (1) Digital radiography (DR) examination shows an enlarged heart shadow with a ”pear-shaped” appearance and a cardiothoracic ratio of approximately 0.65 (Figure.1). (2) Ultrasonography (US) shows an enlarged left atrium with a cystic solid component mass measuring approximately 10.2 cm × 9.9 cm in the pericardial cavity to the left of the heart, squeezing the heart forward (Figure.2). (3) Computed tomography (CT) examination shows a cystic hypodense shadow with well-defined borders on the left edge of the pericardium, with a CT value of approximately 22 HU, and no significant enhancement on enhancement. The left ventricle was compressed and the left ventricular myocardium was thickened compared to the right ventricular myocardium (Figure.3). left pericardial cyst is considered. (4) Cardiac magnetic resonance (CMR) examination shows a mass measuring approximately 10.9 cm × 7.3 cm × 10.4 cm (LR×AP×SI) in the pericardial region outside the lateral wall of the left ventricle was clearly demarcated from the myocardium, and no significant infiltration was seen. The mass shows isointensity on T1-weighted images (T1WI), slightly mixed hyperintensity on T2-weighted images (T2WI), and significantly inhomogeneous high signal on fat-saturated T2WI, with speckled low signal seen locally. Delayed enhancement scan shows a strip of flocculent soft tissue density shadow with heterogeneous mild enhancement within the lesion (Figure.4). The left ventricular chambers were compressed and diastolic motion was limited, with a reduction in end-diastolic and end-systolic volumes of 43.48 ml and 10.88 ml, respectively. (5) Lower extremity magnetic resonance imaging (MRI) examination shows irregularly shaped mass measuring approximately 6.3 cm × 5.7 cm × 6.4 cm (LR×AP×SI) with still clear borders in the left inguinal region. The mass shows low signal on T1WI, and significantly inhomogeneous high signal on fat-saturated T2WI. The lesion was heterogeneously enhanced on enhancement scan and was poorly demarcated from the left external iliac artery. A round-like mass measuring approximately 2.4 cm × 3.0 cm × 3.0 cm (LR×AP×SI) was seen on the left posterior femur, the mass shows low signal on T1WI, and mixed hyperintensity on fat-saturated T2WI, irregular strips of low signal are seen within it, edge undercooling, enhancement shows significant inhomogeneous strengthening (Figure.5). (6) Positron emission tomography (PET) examination shows large lamellar hypodense shadow in the left pericardium with slightly concentrated radiological distribution, SUVmax about 2.6, CT value about 16 HU. Multiple hypodense masses were seen in the left inguinal region and left popliteal fossa with slightly dense radiological distribution, SUVmax about 2.9, larger size about 3.4 cm×5.4 cm, CT value about 26 HU (Figure.6).
Patient undergoes CT-guided pericardial mass puncture, the pathological tissue after puncture shows a dense arrangement of homogeneous round-forming lipocytes and large, circular, ring-like adipocytes on light microscopy, and pathological nuclear schizophrenia was common. Immunohistochemistry shows AE1/AE3 (-), Vimentin (+), SMA (-), Desmin (-), CD34 (vascular+), S-100 (-), INI-1 (+), Caldesmon (-), CD68 (-), Ki-67 (10%+). Clinician diagnosed MLS pericardial metastasis in combination with immunohistochemistry and previous medical history (Figure.7).
The patient and his family refused to undergo pericardial surgery and continued with the previous adjuvant regimen for the 3rd cycle of chemotherapy, along with liver-protective, stomach-protective and immune-boosting drugs. At the end of chemotherapy, the patient’s condition stabilized and the patient and his family requested to be discharged, and the patient died at 5 months of follow-up after discharge.