Pseudotumor inflammatory of the spleen: A rare entity with diagnostic and therapeutic challenges: A case report

Introduction and importance Inflammatory pseudotumor (IPT) of the spleen is a rare entity that can be difficult distinguishing it from malignancies, both in clinical presentation and radiological imaging. Case presentation We present the case of a 43-year-old female presented with 15-cm left hypochondrial mass, Initial imaging studies raised concerns of malignancy, leading to a splenectomy. However, the final pathological examination determined that the patient had IPT of the spleen with focal expression of Smooth Muscle Antibody (SMA). Clinical discussion This case highlights the importance of considering IPT as a potential diagnosis of splenic masses that was difficult to diagnose before surgery. Conclusion The uniqueness of the case under consideration lies in the rarity and the atypical localization of IPT of the spleen.


Introduction
Inflammatory pseudotumors are benign conditions with unknown etiology [1,2].They manifest as localized lesions in the spleen, characterized by the presence of fibroblastic growths and infiltration of various types of inflammatory cells, all of which are reactive in nature.All organs can be affected but they tend to occur more in the orbits and the respiratory system.Splenic localization is extremely rare and only a few cases have been reported in the literature [3].Despite advancements in imaging technologies, preoperative diagnosis of inflammatory pseudotumor of the spleen (IPT) remains a challenging task and is seldom achieved [4].
By using the 2023 Scare model [24], we report a case of a patient presenting an IPT of the spleen treated by splenectomy, with a literature review.

Presentation of case
A 43-year-old woman without any medical history, reported an upper left quadrant abdominal pain over the last year.Physical examination revealed a 15 cm solid mass, fixed to the left hypochondrium, her blood test was normal, except for a microcytic anemia with Hemoglobin level of 7 g/dl.
Ultrasonography and injected abdominal CT-scan showed a voluminous splenic mass of superior polar origin, roughly rounded, with well-defined boundaries, with clean walls presenting an irregular and nodular way enhancement, and the central area within the mass appeared necrotic and did not enhance with contrast.The mass pushes the left liver and stomach without signs of invasion and the splenic hilum was displaced downward with an intact splenic pedicle, and the left kidney was displaced and positioned medially (Fig. 1).
With such findings splenectomy was recommended.Due to the size of the mass, a laparoscopic approach was impossible, leading to the adoption of a median supra umbilical incision, while surgical exploration found a large splenic mass, in contact with the splenic hilum, with dilatation of the splenic vein.
We first started by dissecting and ligating the splenic artery while leaving the spleen in place, then the spleen was mobilized extra abdominally after releasing all its peritoneal attachments.Finally, the splenic vein was ligated and sectioned and the specimen was sent to a pathologist (Fig. 2).
Anatomopathologist received a splenectomy weighing 2 kg 800 g and measuring 30 × 18 × 10 cm.On section, there was a heterogeneous yellowish-white lesion measuring 21 × 12 × 7 cm, and histological analysis revealed that the splenic parenchyma had been replaced by hyalinized fibrosis with areas of necrosis and lymphoid aggregates.Immunohistochemical study showed an intense labeling of spindle cells with the anti-smooth muscle actin (SMA) antibody, while they were negative for the Follicular dendritic cell (FDC) markers CD 23 and CD 21 as well as for the anti-ana-plastic-kinase lymphoma (ALK) and antilatent-membrane protein (LMP1) antibodies.The diagnosis of IPT has been retained (Fig. 3).
The patient's postoperative recovery was uneventful, she received her vaccines against encapsulated germs and she was discharged on the 5th day after surgery.A 10-months follow-up found a patient in good health without showing any kind of complications.

Discussion
Inflammatory pseudotumors are benign conditions that can manifest in different locations including orbit, liver, respiratory and digestive tracts [1,2].
IPT of the spleen is a rare entity characterized by the presence of inflammatory tissue within the spleen, described the first time by Cotelingam and Jaffe in 1984, and until 2016, only 116 cases had been reported (Table 1) [1,3].This condition affects mostly women with a mean age of 47.2 years, although rare cases have been reported in children [4,5].
The precise etiology of this condition remains unknown, several hypotheses have been proposed, including infection, ischemia, trauma, and autoimmune factors [3].
The inflammatory pseudotumor of the spleen was initially described as a proliferation of fibroblastic spindle cells associated with inflammatory cells [1].Arber et al. demonstrated that spindle cells can be either myofibroblasts (actin-positive smooth muscle) or FDC that may be infected by Epstein-Barr Virus (EBV) [6].
Further studies have confirmed the heterogeneity of lesions categorized under the term "inflammatory pseudotumor", encompassing true inflammatory pseudotumors, Inflammatory myofibroblastic tumors (IMT) and inflammatory pseudotumor-like tumors [22].
The presence of necrosis in these lesions suggests an infectious origin although bacteriological examinations and cultures have failed to identify any germ [6].Various characteristics such as necrotic, A: B: C:   hemorrhagic, fibrous or cystic areas have been described [7].
IPT are often asymptomatic, and approximately half of the reported cases were accidentally discovered or during examinations for another disease, such as Hodgkin's disease, idiopathic thrombocytopenic purpura, or hypercalcemia [6,[8][9][10].
Although, they can occasionally manifest with non-specific clinical symptoms, like abdominal pain, fever or weight loss.Clinical examination reveals splenomegaly in 80 % of symptomatic patients as seen in the case presented [1,4,11].
Laboratory findings are usually normal, although hypercalcemia, monoclonal peaks in the proteinogram and polyclonal hypergammaglobulinemia have been reported [1,11].
Due to their strong resemblance to malignancies on imaging, IPT diagnosis is often challenging and conclusive only after splenectomy [8].Franquet et al. reported that the presence of a central stellate area, corresponding to a fibrous plaque after contrast administration strongly suggests an IPT [23].
While CT scans usually reveal a solitary hypodense nodule, which is hypovascular, and sometimes with a central scar [12], MRI may reveal a well-defined mass, isointense on T1-weighted images, and with varying signal intensity on T2, with respect to the surrounding normal spleen [1,4,14].
Preoperative biopsy of the spleen is not recommended due to its low specificity and the risk of bleeding or tumor dissemination in case of malignancy [1], therefore, splenectomy with subsequent evaluation of the surgical specimen is recommended [2,5].
The treatment of inflammatory pseudotumors of the spleen remains surgical, consisting on a total splenectomy, which is the most common approach in the majority of cases reported in the literature.[8] Partial splenectomy, although rarely performed, may be indicated if the splenic tumor is isolated, located far from the hilum, respecting the capsule, and does not invade neighboring organs or nearby lymph nodes [8,15].
Anatomopathological examination allows ruling out primary splenic lymphomas and sarcomas, which are exceedingly rare.Upon histological examination, the inflammatory pseudotumor exhibits well defined boundaries and develops in the red pulp, encompassing islands of white pulp [18].
Cotelingam describes three histological aspects: hypervascularized myxoid foci, compact areas of spindle cells simulating the cellular regions seen in fasciitis or fibromatosis, and large areas of collagenized hypocellular fibrosis [3].
The cellular composition can display significant heterogeneity and share similarities to granulation tissue, notably, normal lymphocytes and plasma cells are consistently present, although their mixture and quantity may vary, and furthermore neutrophilic and eosinophilic leukocytes can also be observed.Despite attempts to classify these lesions, the terminology used to describe this entity is still confusing, and some authors have categorized these lesions into three histopathological subtypes: xanthogranuloma type, plasma cell granuloma type, and sclerosing pseudotumor [6,15,16].
Immunohistochemical studies have shown strong immunoreactivity of spindle cells to vimentin and SMA, thus confirming their myofibroblastic nature [22].
The prognosis after splenectomy is generally favorable, and local invasion, recurrence, or metastasis have not been reported.However, clinical follow-up is recommended, as there have been cases of patients with inflammatory pseudotumors of the liver who have experienced disease related complications [1,2,16].
In conclusion, our case report highlights the importance of considering pseudotumors in the differential diagnosis of splenic masses .Although rare, these lesions can mimic malignant tumors, and accurate diagnosis is crucial for appropriate management .Immunohistochemistry can be a useful tool in the diagnosis of pseudotumors and further studies are needed to better understand the pathogenesis of these lesions .

Consent of publication
Written informed consent was obtained from the patient for publication of this case report and accompanying images.A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Ethical approval
Ethical approval is exempt/waived at our institution.

CRediT authorship contribution statement
MR and AH designed the paper.HO and HS collected the data, HO, and BIK wrote the first draft of the manuscript.FZ did the histopathology study.HS and AH participated in the article design and critically reviewed the manuscript.BIK, HS, AH and MR critically reviewed the manuscript.All authors approved the final version of the manuscript.

Declaration of competing interest
N/A

Fig. 2 .
Fig. 2. Per operative picture after removing the spleen from abdominal cavity.

Table 1
Clinic, radiology and pathology of the reported cases.