Splenic tumors have a low incidence and are rare clinical diseases. Since Rokitansky first described splenic malformation tumor in 1861, sporadic cases or small number of cases have been reported in domestic and international literature. However, with the continuous development of medical imaging technology, the diagnostic accuracy of splenic tumors has been improving. (A) The chief complaint was found to be an occupying lesion in the spleen for 1 week. (B) Medical history The patient was a 54-year-old female, and the spleen was found to be an occupying lesion by ultrasound 1 week ago without any uncomfortable symptoms. (C) Physical examination did not show any positive signs. (D) Auxiliary examination: MRI and enhanced CT of the abdomen were considered as possible “splenic hemangioma”. (E) Treatment After admission, the clinical diagnosis of “splenic hemangioma” was clear, followed by laparoscopic splenectomy under general anesthesia. The postoperative pathology diagnosed “splenic hemangioma”. The patient recovered well after surgery and was discharged on the 6th day after surgery. Case 2: Splenic cyst Case presentation (a) The chief complaint was that an occupied spleen had been found on examination for 2 months. (b) Medical history The patient was a 67-year-old male who was hospitalized 2 months ago for “prostatic hyperplasia” when he underwent an abdominal CT examination and was found to have an occupying splenic lesion, which was considered a splenic cyst. He had no previous history of trauma or surgery, no history of living or residing in an infected area, and no history of pet ownership or contact. This admission required surgery. (C) No positive signs on physical examination. (D) Ancillary examination CT examination (Figure 2): the spleen was significantly enlarged, and a 9.0×10.4 cm round low-density lesion with clear boundaries was seen in its upper pole, with no enhancement after enhancement. Impression: benign occupying lesion in the spleen, considering a possible splenic cyst. (V) Treatment After admission, the clinical diagnosis of “splenic cyst” was clearly established by combining the medical history and CT imaging features. Subsequently, an open splenectomy under general anesthesia was performed. The postoperative pathology diagnosed “true cyst of the spleen”. The postoperative recovery was smooth and he was discharged on the 8th day after surgery. Case 3: Chronic granuloma of the spleen Case presentation (a) The chief complaint was a 10-day history of splenic occupancy. (b) Medical history The patient was a 53-year-old male who was admitted to the hospital for 10 days with an occupying spleen lesion on examination. After admission, ultrasound and CT examination of the abdomen were performed and “splenic malformation tumor” was suspected. He had undergone gastric repair for peptic ulcer perforation 17 years ago and denied previous history of tuberculosis. He was admitted to the hospital for surgery. (C) Physical examination was not positive except for the old incisional scar in the upper abdomen. (D) Auxiliary examination chest X-ray: old tuberculosis in the right upper lung. CT examination (Figure 3A-C): The spleen was enlarged and a 10×7×6 cm solid occupancy with poorly defined borders was seen in the middle and lower pole, with scattered calcified spots within. Enhancement of the lesion was weaker than normal splenic parenchyma. Impression: splenic malformation tumor is likely. (E) Treatment After admission, the clinical diagnosis of “benign tumor of spleen: malformation tumor?” was made after combining the medical history and CT imaging features. The indication for surgery was clear. Subsequently, an open splenectomy under general anesthesia was performed. The spleen was completely resected, and the splenic envelope was intact. The postoperative pathology diagnosed “chronic granulomatous inflammation of the spleen, not excluding tuberculosis; serological indicators related to tuberculosis are recommended”. Tuberculosis chest X-ray confirmed “old tuberculosis of the right upper lung”, and the discharge diagnosis was “chronic tuberculosis granulomatous inflammation of the spleen”. The postoperative recovery was smooth, and he was discharged on the 7th postoperative day. Case 4 Metastatic carcinoma of the spleen Case presentation (a) Complaint: 4 months after resection of giant right hepatocellular carcinoma, an occupying lesion of the spleen was found for 1 week. (b) Medical history The patient was a 53-year-old male who underwent transhepatic artery embolization chemotherapy (TACE) for giant right hepatocellular carcinoma diagnosed 5 months ago, and right hepatocellular carcinoma resection was performed 2 months after TACE. Postoperative recovery was smooth. Pre-operative AFP was >10000ng/ml and recovered normally after surgery. After the operation, regular review of abdominal ultrasound and AFP was given, and adjuvant TACE was performed twice. The AFP increased to 800ng/ml at 3 months after surgery, and there was no clear recurrent lesion in the liver on review. Enhanced CT examination suggested metastatic cancer in the spleen. (C) Physical examination: A reverse “L” incision scar was seen in the right upper abdomen, but the rest was not abnormal. (D) Ancillary examination: Enhanced CT examination (Figure 1): a type of round low-density solid lesion at the posterior edge of the spleen, with no significant enhancement in the arterial phase and peripheral enhancement in the venous phase and delayed phase, and homogeneous parenchyma of the lesion. (V) Treatment After admission, the clinical diagnosis of “metastatic carcinoma of the spleen, postoperative hepatocellular carcinoma” was confirmed by the medical history, CT images and AFP level. Subsequently, laparoscopic exploration and radiofrequency ablation of spleen tumor were performed under general anesthesia. A small incision was chosen on the left side of the umbilicus, and a 10-mm Trocar hole was established after the establishment of pneumoperitoneum to place the laparoscopic lens, and it was observed that the right upper abdominal cavity had severe abdominal adhesions and the left upper abdominal splenic fossa had a few fibrinous adhesions. In addition, 10-mm and 5-mm Trocar holes were established at the midline of the clavicle below the left costal margin and to the left of the subclavian incision, respectively (Figure 2A). After separating the perisplenic adhesions, the splenic colonic ligament and splenorenal ligament at the lower pole of the spleen were fully freed, and the two overlapping sites of the splenic tumor area were treated with ablation using a set of RF electrodes (Figure 2). The postoperative recovery was smooth, and the patient was discharged on the third postoperative day. He was discharged on the 3rd postoperative day. However, he had sudden syncope and blindness on the 7th postoperative day, and the cranial CT suggested intracranial metastasis of the tumor. It was not rechecked afterwards. Bostick et al. reported that only 5 cases were found in 17,707 autopsies and 68,820 surgical specimens; in China, Sun Chongbo et al. reported that there were only 18 primary tumors of the spleen among 86,160 cases. Because of the extremely low incidence, it often leads to the lack of awareness of splenic tumors among clinicians. (A) There is no uniform standard for the classification of spleen tumors. According to the site of tumor occurrence, splenic tumors can be divided into two categories: primary and metastatic. According to the origin of tissue components, primary splenic tumors are divided into four types: ① Tumor-like lesions: splenic cysts and misshapen tumors are common. Splenic cysts can be subdivided into parasitic and nonparasitic cysts, with the latter being subdivided into true and pseudocysts. True cysts have epithelial or epithelial cell lining within the cyst wall and are often isolated, unicompartmental cysts. Pseudocysts consist of fibrous tissue forming the cyst wall, and their occurrence is associated with the formation of a confined cystic cavity and liquefaction following splenic rupture and bleeding, inflammation, arterial or lymphatic vessel infarction; malformation tumors are due to developmental abnormalities that alter the proportion of combinations of the normal constituent components of the spleen. (ii) Tumors of vascular origin: including benign and malignant lesions, of which benign ones are predominant, including spongy or capillary angiomas, littoral cell angioma, angiosarcoma, etc. (iii) Lymphatic tumors: they consist of cystic expansion of lymphatic vessels due to abnormal development of local lymphatic vessels, such as lymphangioleioma and lymphoma. ④ Non-lymphoid tumors, such as inflammatory pseudotumors. Common primary malignant tumors of the spleen include: ① Angiosarcoma: sarcoma formed by malignant proliferation of vascular endothelial cells. Its clinical characteristics are splenomegaly with hepatomegaly, spontaneous splenic rupture in some cases, and susceptibility to distant metastases to liver, bone and lung. ② Primary lymphoma: It is the most common malignant tumor of the spleen and refers to malignant tumors originating from the lymphoid tissue of the spleen, including primary Hodgkin’s disease and non-Hodgkin’s lymphoma. ③ Other primary malignant tumors of the spleen are rare, such as smooth muscle sarcoma, liposarcoma and malignant nerve sheath tumor. Among benign tumors, splenic hemangioma is the most common, which is caused by abnormal embryonic development of splenic vascular tissue. Spongiotic hemangiomas of the splenic parenchyma predominate, and they can also be capillary hemangiomas, the latter often appearing as limited or multiple capillary masses. Splenic hemangiomas are characterized by slow growth, gradual increase in size, and in severe cases, the entire spleen may be involved. Secondary lesions such as infarction, infection, fibrosis, and calcification may occur in splenic hemangiomas. Splenic lymphangioadenoma has the second highest incidence among benign tumors of the spleen. There are three types of splenic lymphadenoma: (1) simple lymphadenoma; (2) cavernous lymphadenoma; and (3) cystic lymphadenoma. CT scan shows an enlarged spleen with intrapleural cystic hypodensity, clear contours, and CT values of 10-30 HU, with coarse internal septa and mild enhancement, unlike simple splenic cysts. (2) Clinical manifestations of splenic tumors lack specific clinical manifestations, especially for early or small benign lesions, which usually have no obvious clinical symptoms and positive signs and are only discovered accidentally during physical examination. Only when the size of spleen tumor increases to a certain extent and presses the surrounding organs, discomfort and distension in the left upper abdomen may occur, and the abdominal pain is mostly dull or distending. The symptoms of compression of surrounding organs caused by tumor mainly include gastrointestinal symptoms, such as abdominal distension, nausea, vomiting and constipation. When the spleen volume increases rapidly in a short period of time, the local symptoms are more obvious due to excessive stretching of the splenic envelope. Malignant tumor of spleen may be accompanied by various degrees of systemic symptoms, such as low fever, dizziness, fatigue, anemia, weight loss and cachexia, and occasionally leukocytopenia and thrombocytopenia. If the spleen tumor is combined with infection, high fever of unknown origin may occur. If the spleen tumor ruptures spontaneously and bleeds, the clinical symptoms are obvious, with sudden severe pain in the left upper abdomen, intra-abdominal hemorrhage and hemorrhagic shock. Among the primary tumors of the spleen, angiosarcoma is the most prone to spontaneous rupture, and tumor rupture may also cause metastasis of tumor cells in the abdominal cavity. CT and MRI manifestations of splenic vascular tumors pathology CT imaging MRI imaging angiosarcoma vascular access, endothelial lining, blood filling; capillary, spongy, or mixed; hemorrhage, infarction, or thrombosis; single or multiple solid or cystic components, curvilinear or eggshell shaped calcified enhancing lesions may have subacute hemorrhagic areas T1WI low signal T2WI high signal centripetal enhancing hemorrhagic areas lymphatics Tumor cystic, endothelium-lined, proteinous fluid-filled capillary lymphatics, spongy or cystic hypointense areas without enhancement (swiss cheese appearance) Curvilinear calcification T1WI and T2WI intermediate signal or high signal misshapen tumor normal splenic tissue (white marrow, red marrow, or both) well-defined focal contour abnormalities; calcified cystic and/or solid components T1WI isosignal T2WI ultrahigh signal heterogeneous, delayed-enhancing angiosarcoma focal or diffuse involvement; cystic or solid; spontaneous ruptured hemorrhage; multiple metastases to liver, lung, bone, and lymphatic system giant spleen; poorly defined, hypointense borders; may have calcification; necrotic, hemorrhagic component; multiple enhancing forms giant spleen; hemorrhagic nodules; areas of necrosis Vanhoenacker FM, et al. Semin Ultrasound CT MR, 2007,28(1):35-51. Most splenic metastases have a clear primary malignant lesion. Common primary tumors include lung cancer, breast cancer, colon cancer, malignant melanoma, ovarian cancer, prostate cancer, liver cancer, cervical cancer, and pancreatic cancer. Metastatic cancer of the spleen mostly originates from the hematogenous metastasis of tumor cells, and a few can be direct infiltration of tumors, such as direct invasion of the spleen by tumors in adjacent anatomical locations such as the stomach, colon, and left kidney. Bai Xiaofeng et al. reported the clinical data of 43 cases of primary spleen tumors, including 15 cases of splenic hemangioma, 16 cases of splenic lymphoma, 8 cases of splenic hemangiosarcoma, 1 case each of splenic lymphangioleiomyoblastoma, myofibroblastoma, inflammatory pseudotumor and splenic sarcoidosis, with malignant tumors accounting for 56% (24 cases). 21 cases (49%) had no clinical manifestations and were discovered accidentally during physical examination; 13 cases only had non-specific abdominal discomfort or vague pain; 6 cases had abdominal discomfort or vague pain. In 6 cases, abdominal mass was the first symptom; in 3 cases, sudden abdominal pain was found in emergency surgery. Eleven patients with malignant tumors had symptoms such as splenomegaly, thrombocytopenia, fever, anemia, and wasting. (III) Diagnosis Primary splenic tumors are mostly asymptomatic or mildly symptomatic in the early stage, which makes the diagnosis more difficult, and their clinical manifestations are non-specific, so the diagnosis is easily delayed. With the development of ultrasound, ultrasonography, CT, MRI and fine-needle aspiration (FNA), the preoperative diagnosis of spleen tumor has become possible. B-mode ultrasonography is non-invasive, economical and convenient, and is often used as the first choice for the diagnosis of splenic occupying lesions. It can understand the presence or absence of tumor, its location, size and scope, the presence or absence of envelope, identify the cystic solidity of tumor and the relationship with surrounding organs. However, ultrasound is affected by factors such as intestinal gas interference, obesity and operator’s technical level, and smaller tumors (≤1 cm) are difficult to be detected, therefore, its accuracy is still insufficient. High-resolution color Doppler ultrasound can help determine the nature of splenic tumors based on the presence or absence of blood flow inside the tumor and how much it is, and CT can provide more accurate images of the location, number, size, extent, relationship with neighboring organs and lymph node metastasis of the tumor, which can facilitate more accurate judgment of the disease before surgery. It is the most valuable imaging tool to diagnose small spleen tumors (≤1 cm), which can be seen on X-ray as irregularly enlarged splenic shadows, elevation of the left diaphragm, reduced activity, and inward and downward displacement of the splenic flexure of the kidney and colon. Selective splenic arteriography is of value in the diagnosis and differential diagnosis of splenic tumors. Benign tumors show compressive changes of arterial branches, while malignant tumors show vascular disruption, displacement, irregular luminal narrowing, and irregular distribution of neovascularization. Although imaging examination is important for the diagnosis of splenic tumors, it has some limitations. Regardless of the examination method, the final diagnosis depends on surgical exploration and pathological diagnosis. When the Casoni intradermal test is positive and other parts of the body are clearly encrusted with worm disease the possibility of splenic encrusted cysts should be considered. In recent years, fine-needle aspiration (FNA) biopsy of the spleen guided by ultrasound or CT has been increasingly reported. This technique provides a definitive pathologic diagnosis and is gradually being promoted by imaging physicians. However, the splenic blood supply is rich and brittle, and the concern of splenic bleeding after the operation is the biggest obstacle to the promotion of FNA technique. The indications for FNA are: (1) malignant lymphoma suspected to invade the spleen; (2) hematologic disease requiring clarification of the type or understanding of the function of the spleen; (3) cystic lesion of the spleen requiring aspiration and drainage or imaging to confirm the diagnosis; (4) substantial mass of the spleen requiring pathologic histological confirmation. (iv) Treatment Because of the risk of infection and rupture of spleen tumor, and the nature of spleen tumor is difficult to determine, and the possibility of malignant lesion cannot be excluded. Therefore, unless the diagnosis is clear for smaller benign spleen lesions, active surgical treatment should be considered once spleen tumors are detected. According to the different pathological types of spleen tumors, appropriate surgical methods should be selected. 1.Spleen cyst: For smaller spleen cysts, no surgical treatment can be suspended and regular follow up and observation. For larger splenic cysts, once diagnosed, surgery should be chosen as early as possible, otherwise there is a risk of intracapsular infection and rupture. The surgical procedure for splenic cysts should be decided according to the site, size and nature of the cyst, and can be performed by cyst opening and drainage or partial splenectomy or total splenectomy. Total splenectomy is feasible if the cyst is located at the splenic hilum or in the middle of the splenic body. If the cyst is located in the middle of the splenic portal or body, total splenectomy can be performed. If the cyst is located in the superior or inferior pole of the spleen, partial splenectomy is possible. If necessary, a rapid pathological examination should be performed intraoperatively to avoid missing the malignant tumor. 2.Spleen abscess: puncture and drainage can be performed under the guidance of B-ultrasound, and partial splenectomy or splenectomy is feasible if the abscess is separated or recurrent. 3.Benign tumor of spleen: With the deeper understanding of immune function of spleen, there is an increasing tendency to perform spleen-preserving surgery. For benign tumor of spleen, part of the spleen parenchyma should be preserved as much as possible to maintain the function of spleen under the premise of ensuring radical treatment. In particular, in young children with small lesions, partial splenectomy or intra-retinal transplantation of splenic tissue pieces or partial splenic transplantation with vascular tissues is preferable because of the possibility of postoperative OPSI or benign tumors limited to a certain segment. When performing splenopexy, special attention should be paid to the following: splenic tumors that are diagnosed by intraoperative rapid pathology can be performed only if they are benign; splenic tumors can be multicentric and multifocal in distribution, so partial splenectomy may not be able to remove all the lesions, so sufficient resection of splenic hemangioma or lymphadenoma lesions should be performed to avoid postoperative recurrence. If intraoperative rapid pathological section cannot exclude malignant tumor, total splenectomy should be performed. 4.Primary malignant tumor of the spleen: For confirmed malignant tumor of the spleen, radical surgical resection should be performed. That is, splenectomy plus lymph node dissection of splenic hilum, and if necessary, combined organ resection such as pancreatic tail. After surgery, adjuvant therapy should be added according to the type of pathology. The prognosis of primary malignant tumors of the spleen is closely related to the stage and pathological type of the disease. Early diagnosis, early radical surgical treatment and adjuvant chemotherapy and radiotherapy are the keys to improve the efficacy of primary malignant tumors of the spleen. In recent years, minimally invasive surgical techniques have developed rapidly, and laparoscopic splenectomy has gradually increased, which is less invasive, simple to operate and has fast postoperative recovery, but it has raised higher requirements for the identification of benign and malignant splenic tumors before surgery, which has been reported and found. There is a significant increase in abdominal Trocar implant metastasis after laparoscopic splenectomy for primary malignant tumors of the spleen. In addition, with the advancement of minimally invasive concepts and the tremendous progress in ablation techniques such as radiofrequency ablation and microwave ablation, successful radiofrequency ablation of splenic parenchyma or splenic tumors has been reported. The case of radiofrequency ablation of metastatic carcinoma of the spleen reported in this paper is the third case in the literature. The first two cases were metastatic cancer of the spleen secondary to kidney cancer and colon cancer, respectively.