Japanese Journal of Clinical Oncology 30:196-203 (2000)
© 2000 Foundation for Promotion of Cancer Research
Inflammatory Pseudotumor of the Spleen: A Case Report
1Department of Surgery, Kondo Hospital, Okayama, 2Department of Radiology, Ochiai Hospital, Okayama and 3Department of Pathology, Kawasaki Hospital, Okayama, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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We report on an inflammatory pseudotumor of the spleen. A 72-year-old woman visited our hospital complaining of nausea. Physical examination and laboratory investigations were unremarkable. Ultrasonography, computed tomography, magnetic resonance imaging and angiography showed a hypovascular splenic mass measurinsg about 5 cm in diameter with a calcification in the center of the lesion. Splenectomy was performed. The removed spleen, weighing 145 g, contained a tan-white, circumscribed mass, measuring 6.2 x 5.5 x 5.3 cm. Histologically, the splenic mass was composed of an admixture of inflammatory cellular elements, predominantly plasma cells and lymphocytes with hyalinization, fibrosis, lymph follicles and multinuclear giant cells, suggestive of a inflammatory pseudotumor. The patient is currently alive and asymptomatic, 24 months after surgery. Inflammatory pseudotumors of the spleen are extremely rare and only 39 cases have been reported in the medical literature.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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Inflammatory pseudotumors are benign entities of unknown etiology and pathogenesis. They have been observed in various parts of the body, including the orbit, respiratory tract, gastrointestinal tract and soft tissues, lymph nodes and liver (1,2). However, inflammatory pseudotumors in the spleen are extremely rare and are frequently misdiagnosed as malignant neoplasms or other benign tumors. To our knowledge, only 39 well-documented cases of inflammatory pseudotumor of the spleen have been reported in the medical literature since 1984 (1–28) (Table 1). Although recent advances in imaging techniques, such as ultrasonography (US), computed tomography (CT) and magnetic resonance imaging (MRI), have aided in the identification of space-occupying lesions of the spleen, these techniques do not permit preoperative diagnosis of these lesions.
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In this paper, we describe a case of inflammatory pseudotumor of the spleen.
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CASE REPORT |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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A 72-year-old woman visited our hospital complaining of nausea. There was no history of constitutional symptoms, overseas travel, intravenous drug ingestion, trauma or alcohol abuse. Nor was there any family history of similar illnesses. Physical examination did not reveal organomegaly or lymphadenopathy. Laboratory findings registered in the normal ranges, including a leukocyte count of 5100/mm3 without a shift to the left.
A splenic mass lesion was discovered incidentally by ultrasound examination. Abdominal US showed a hypoechoic splenic mass measuring 6.2 x 4.4 cm in diameter with a calcification in the center of the lesion. Abdominal CT confirmed the existence of a partially calcified, low-density, hypovascular, well-defined, round, smooth mass. Abdominal MRI also revealed the splenic mass. The mass showed low to iso-intensity on T1-weighted images (Fig. 1) and high intensity with surrounding low intensity on T2-weighted images. This was accompanied by low intensity in the center of the lesion (Fig. 2). Dynamic MRI showed that the mass enhanced from outside and later than benign splenic parenchyma. The center of the lesion, which was low intensity on T2-weighted images, was not enhanced. This area corresponded to the calcification (Fig. 3). Angiography revealed a hypovascular area in the arterial phase. At first, we supposed that the mass was metastasis, but primary lesion was not detected, although gastrointestinal endoscopy, colonoscopy and other examinations were performed. On gastrointestinal endoscopy, it was discovered that the patient had gastritis and slightly sliding hernia of the esophagus. Therefore, it was thought that the symptom of nausea was due to gastritis and sliding hernia, not to inflammatory pseudotumor.
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We suspected that the mass was hemangioma, hematoma, inflammatory pseudotumor or malignant lymphoma. Laparotomy was performed 12 days after admission because in the splenic mass it was difficult to distinguish inflammatory pseudotumor from malignant tumor. On laparotomy, the liver, kidneys, uterus and lymph nodes were unremarkable. The mass was adherent to surrounding structures, such as the greature omentum and peritoneum, but other organs had not been invaded. Therefore, splenectomy was performed. The postoperative course was uneventful. The patient is currently alive and asymptomatic, 24 months after surgery.
The spleen weighed 145 g and measured 8.5 x 7.0 x 5.5 cm. The mass was roughly round, elastically hard and the cut surface of the mass was well-circumscribed, lobulated, tan-white and bulging (Fig. 4), measuring 6.2 x 5.5 x 5.3 cm in diameter. The mass compressed the adjacent splenic parenchyma. In the center of the lesion, there was a white calcification and soft necrotic area. Histologically, the splenic architecture was totally effaced in the area of lesion. There was a large, irregularly shaped focus of necrosis in the center, with a marked inflammatory infiltratration composed of an admixture of inflammatory cellular elements, predominantly plasma cells and lymphocytes with hyalinization, fibrosis, lymph follicles and multinuclear giant cells (Figs 5 and 6). No acid-fast organisms, fungi, parasites, bacteria or birefringent material were found. EBV was not detected on in situ hybridization. S-100 protein and SMA were negative on immunostaining. A final diagnosis of inflammatory pseudotumor was made.
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONCASE REPORTDISCUSSIONREFERENCES |
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The incidence of benign splenic tumors is 0.007% among all subjects on whom an operation or autopsy (18) is performed. Inflammatory pseudotumors of the spleen are extremely rare and only 39 cases, including the present case, have been reported in the literature since the initial report of two cases by Cotelingam and Jaffe in 1984 (1–28). Based on these reports, it appears that inflammatory pseudotumors of the spleen occur most often in middle-aged or older persons of both genders. The clinical signs and symptoms are most diverse, with pain in the left flank or hypocondrium associated in some cases with fever or splenomegaly, while in other cases there were symptoms that were not specific to the disease. Hypercalcemia (13), monoclonal peaks in the proteinogram (2) and polyclonal hypergammaglobulinemia (8) that disappeared after splenectomy have also been reported. Inflammatory pseudotumors of the spleen frequently are found incidentally, without evidence of prominent infection, as a solitary mass in the spleen, as occurred in our patient. In some cases, laboratory studies showed anemia and leukocytosis due to the chronic inflammation. In the previously reported cases, although the presence of a splenic mass was verified preoperatively, a preoperative diagnosis of pseudotumor was not made.
Splenic inflammatory pseudotumor is a benign condition that should not be confused with neoplasms. As suggested previously, it is of utmost clinical importance to distinguish a splenic inflammatory pseudotumor from a primary splenic lymphoma or hamartoma (1,6,8,14). However, splenic inflammatory pseudotumors frequently mimic other splenic neoplasms clinically and radiologically (1,5,6,14). Most frequently CT and US have been used to detect splenic inflammatory pseudotumors in previously reported cases. However, the findings in these cases were not sufficiently specific to differentiate this type of lesion from other neoplasms, including lymphomas or hamartomas (1,8,14). In this case, non-enhanced CT examination revealed a hypodense mass with calcification, which showed heterogeneous enhancement after contrast injection. The usual differential diagnoses of splenic masses with calcification include splenic cyst, hamartoma, hemangioma, lymphangioma and plasmacytoma. Franquet et al. (6) reported that the presence of a central satellite area corresponding to a fibrous plaque on CT examination after contrast administration is strongly suggestive of an inflammatory pseudotumor.
In several cases, MRI has been applied to inflammatory pseudotumors of the spleen, but the reported findings also seem insufficient to diagnose this benign entity, even when contrast agents are administered (14). In our case, MRI examination proved useful for assessing the internal structure. The mass showed low to iso-intensity on T1-weighted images and high intensity with surrounding low intensity on T2-weighted images. This was accompanied by low intensity in the center of the lesion. The surrounding low-intensity area on the T2-weighted images corresponded to a focal area of fibrosis showing a clear pathological correlation with the gross specimen. Dynamic MRI showed that the mass enhanced from outside and later than benign splenic parenchyma. The center of the lesion, which was low intensity on T2-weighted images, was not enhanced. This area corresponded to calcification.
At present, neither modern imaging techniques, such as echo, CT and MRI, nor fine needle aspiration cytology (2,25) allow for a preoperative diagnosis of inflammatory pseudotumor. Differential diagnosis must be made with several diseases, such as abscess, hemangioma, angiosarcoma, malignant lymphoma and hamartoma (2). Splenic abscesses are considered less likely because of the long duration of the lesion and lack of a fluid component. The lack of calcification and fatty elements argues against splenic hemangioma or angiosarcoma, whereas the lack of a cystic configuration argues against lymphangioma. However, primary splenic lymphoma or hamartoma remain in the differential diagnosis (28). The microscopic findings, however, are characteristic and the diagnosis can be made readily by identifying the reactive nature of the cells. The cellular composition of inflammatory pseudotumors can be remarkably heterogeneous (8). Inflammatory pseudotumors of the spleen show some resemblance to granulation tissue and normal lymphocytes and plasma cells are constant features, although in variable mixtures and numbers (1–28). Neutrophilic and eosinophilic leukocytes are also sometimes present (1,8). Someren (29) classified this lesion into three types: xanthogranuloma, plasma cell granuloma and sclerosing pseudotumor. However, some reports used a differential classification. The terminology used when referring to this group of lesions is confusing. The same term has been applied to different entities and the same entity may be referred to by different names, reflecting a lack of unified definition and differing views on the nature of the lesion. Thus Chan (30) classified in the interim, such as infective type, reparative type, myofibroblastic tumor type, follicular dendritic cell type and not otherwise specified.
The term ‘inflammatory pseudotumor’ has been used for a variety of chronic sclerosing inflammatory processes with a distinct histopathological appearance. Although the etiology and pathogenesis of this entity are unknown, infections, vascular causes and autoimmune disorders have been hypothesized in their pathogenesis (1,5,8,31). Infection is one hypothesis, because of the presence of granulomas and giant cells. However, this theory is doubtful because no evidence of infectious organisms could be demonstrated in any of the reported pseudotumors or related entities (29). Some cases were reported to be Epstein–Barr virus (EBV)-positive inflammatory follicular dendritic cell tumors (30). In our case, no acid-fast organisms, fungi, parasites, bacteria or birefringent material could be identified and EBV was not detected on in situ hybridization. Vascular causes is another hypothesis and it is believed by some that these lesions may be due to intraparencymatous hemorrhage secondary to traumatism or coagulopathy. Only one case had antecedents of traumatism (14). Cotelingam and Jaffe (3) suggested the main initial event may have been a focal parenchymal necrosis with hemorrhage. In our case, no evidence of underlying vascular changes were observed. The high content of plasma cells in this lesion suggests the theory of an immunological origin as another hypothesis (32). Someren (29) supports this idea because of the histological similarities between this entity and processes of recognized autoimmune origin.
The prognosis of inflammatory pseudotumor of the spleen has generally been considered favorable after splenectomy according to the previously published cases. After removal of the lesion there have been no reports of metastatic disease, local invasion or recurrence. However, careful follow-up is necessary, since some patients with inflammatory pseudotumors of the liver are reported probably to have died as a result of the disease (33).
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FOOTNOTES |
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+ For reprints and all correspondence: Hirofumi Noguchi, First Department of Surgery, Okayama University Medical School, 2–5–1 Shikatacho, Okayama 700-8558, Japan
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Received November 8, 1999; accepted January 26, 2000.
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