Calcifying fibrous pseudotumor of mediastinum--a case report

Multiple calcifying fibrous tumors from gastric and retroperitoneal tissue: A case report

INTRODUCTION AND IMPORTANCE

Calcifying fibrous tumor (CFT) is a rare benign mesenchymal lesion that has been occurred in the gastrointestinal tract, especially occurs most commonly in the stomach and the small and large intestines.

CASE PRESENTATION

74-year-old woman was admitted to our hospital with complaints of epigastric discomfort. Whole-body computed tomography (CT) revealed a 2.2-cm mass with a 1.2-cm low-density area at the anterior wall in the gastric cardia and lesser omentum; however, no abnormal uptake at the same site was noted on positron emission tomography (PET). We performed laparoscopic tumor resection of the two sites. The postoperative course was good without complications. Histopathological findings revealed collagen fibrous granulation connective tissue and psammomatous calcification. Subsequently, the patient has been relapse-free for 6 months.

CLINICAL DISCUSSION

CFT is a rare benign tumor that commonly occurs in soft tissues, such as the subcutaneous extremities and neck. In particular, development from the stomach and lesser omentum has never been reported. Our case was incidentally found on a general examination. In our case, CT showed a low-density area, MRI showed a low-intensity area, and PET examination showed no uptake; it was difficult to establish a preoperative diagnosis. Therefore, in our case, laparoscopic tumor resection was performed, with GIST as the differential diagnosis.

CONCLUSIONS

We herein reported a rare gastric and lesser omentum CFT that was successfully treated by laparoscopic surgery. For curative treatment of CFT, complete surgical resection is necessary.

Pulmonary Calcifying Fibrous Tumor in a Pediatric Patient: A Case Report

A calcifying fibrous tumor (CFT), also known as calcifying fibrous pseudotumor, is an uncommon non-cancerous neoplasm usually located in the gastrointestinal tract. Its location in the lung is extremely rare, and only a few case reports have been published. This case report describes our diagnostic approach in a 9-year-old male patient with an incidental pulmonary mass. The mass was initially misdiagnosed, requiring multiple imaging tests and interventions to obtain the definitive diagnosis of pulmonary CFT. This paper aims to contribute to the limited information available on pulmonary CFT by presenting detailed findings from computed tomography and magnetic resonance imaging.

Complete Resection of a Large Mediastinal Calcifying Fibrous Tumor

Calcifying fibrous tumor (CFT) is a benign tumor entity which can present in a variety of different sites. Till date, eight cases with a mediastinal manifestation have been published in literature. Surgical removal is the treatment of choice for this often incidentally detected tumor. Surgery of thoracic CFT may be challenging due to its localization within the mediastinum. A 10-year old boy with a right-sided thoracic pectus carinatum-like deformity was referred for further evaluation, incidentally, revealing a mediastinal mass in computed tomography (CT). Laboratory results were all within normal range. Magnetic resonance imaging (MRI) showed a large tumor in the upper anterior mediastinum suggesting expansive but not infiltrative character. The tumor was displacing surrounding structures like the heart and the diaphragm. Lower venous stasis with dilation of the inferior cava vein could be demonstrated. The tumor was considered to be of benign dignity and surgical removal was indicated. Complete tumor resection could be achieved through a sternotomy approach, along with thymectomy. A partial resection of both the pericardium and diaphragm was required due to adhesion with soft tissue at those sites. The specimen's size was 320 mm × 145 mm × 100 mm, histologically confirmed as CFT. The patient showed no residual tumor at 3- and 9-month follow-up. This case is a report on a large mediastinal CFT which underwent successful complete surgical removal. Following tumor resection, prognosis is considered to be good; however, key issue is complete resection to avoid local tumor recurrence.

Calcifying fibrous tumor of the mediastinum: A case report

BACKGROUND

Calcifying fibrous tumor (CFT) is a rare benign mesenchymal tumor that often occurs in deep soft tissue of children and young adults. CFT rarely occurs in the mediastinum.

CASE SUMMARY

In this paper, we describe a 31-year-old male patient with CFT in the mediastinum. The patient did not have any symptoms, and the posterior mediastinal lesion was unintentionally found during routine re-examination of thyroid cancer. The tumor had no adhesion to the surrounding tissue and was successfully and completely removed. Pathology showed a large amount of collagen-rich fibrous connective tissue. There was scattered dystrophic calcification and gravel in the fibrous tissue and a small amount of lymphocyte and plasma cell infiltration and lymphoid follicle formation in the interstitial fluid. In addition, findings showed 20 IgG4+ plasma cells per high-powered field of the diseased tissue, an IgG4+/IgG ratio of about 20%, and normal serum IgG4 levels. The final diagnosis was CFT of the mediastinum (CFTM). No evidence of tumor recurrence was observed by computed tomography at 3 mo after surgery.

CONCLUSION

IgG4+ plasma cell enlargement may occur in CFTM, but clinical manifestations and serological tests suggest that it is not IgG4-related disease. We speculate that it may be an independent tumor subtype.

Whole-exome sequencing identifies unique mutations and copy number losses in calcifying fibrous tumor of the pleura: report of 3 cases and review of the literature

Calcifying fibrous tumor of the pleura (CFTP) is a rare mesenchymal tumor of unknown pathogenesis. The diagnosis often requires exclusion of other common entities. Our aim was to determine if genomic changes were associated with CFTP that could contribute to mechanisms underlying tumorigenesis. Three cases of CFTP with their corresponding uninvolved control lung tissue were identified. Two patients were male, and 1 was female (age range, 21-32 years). Tumors were multifocal in 2 cases and solitary in 1. Immunohistochemistry for STAT6, BCL-2, CD34, cytokeratin AE1/AE3, calretinin, desmin, S100, ALK, and β-catenin was used. All immunohistochemistries were negative in CFTPs. DNA was isolated from all 3 pairs of CFTPs and matching normal lungs for whole-exome sequencing. Damaging, tumor-specific, coding variants were identified in 3 genes including multiple heterozygotic, de novo mutations in the Zinc Finger Protein 717 (ZNF717), fascioscapulohumeral muscular dystrophy-1 (FRG1) and cell division cycle 27 (CDC27) genes. Whole-exome sequencing revealed statistically significant, focal, tumor-specific copy number losses among all CFTPs including a large (302 kb) loss at 6p22.2 comprising 32 genes of the histone cluster 1 family and the hemochromatosis (HFE) gene. This is the first study to evaluate the molecular pathogenesis of CFTP and to identify novel deleterious mutations in ZN717, FRG1, and CDC27 genes as well as significant copy number losses on 8 chromosomes with a large loss common to all samples on chromosome 6. These mutations deleteriously altered coding domains in a manner predicted to be damaging to protein function and may contribute to CFTP tumorigenesis.

Calcifying Fibrous Pseudotumor of the Posterior Mediastinum With Encapsulation of the Thoracic Duct

We report the first case of calcifying fibrous pseudotumor (CFPT) to arise in the posterior mediastinum with encapsulation of the thoracic duct. This exceedingly rare lesion was incidentally discovered in an asymptomatic young woman and treated with surgical resection, requiring ligation and excision of the thoracic duct. There has been no evidence of tumor recurrence or postoperative complication.

Calcifying Fibrous Tumor: Review of 157 Patients Reported in International Literature

Calcifying fibrous tumor (CFT) is a benign lesion characterized by its specific histological findings and is found as solitary or multiple lesions in several locations of the human body. The aim of the present systematic review is to give a detailed account of all reported cases of CFT in the literature and to analyze the available data, to completely characterize the entity from epidemiological, medical, and surgical aspects.A bibliographic research was performed from 1988 until 2015. A database with the patients' characteristics was made, including sex, age, location of the tumor, symptoms, symptoms duration, size of the tumor, diagnostic methods, treatment, metastasis, and follow-up.A total of 104 articles were identified, reporting 157 cases of CFT. Mean age of patients was 33.58 years and the ratio between men and women was 1:1.27. The most common locations of CFT were stomach (18%), small intestine (8.7%), pleura (9.9%), mesentery (5%), and peritoneum (6.8%). Mean diameter of the tumor was estimated 4.6 cm. The correlations proceeded showed that as age increases, size decreases (P = 0.001) and that the tumor is larger in females (P = 0.027). Kruskal-Wallis test showed that the larger tumors appear in the neck and adrenal gland (P = 0.001). The percentage of asymptomatic patients was 30.57%. Computed tomography and biopsy were the most common tests for the diagnosis of CFT. Open surgical procedure was performed in the majority of cases. The median hospitalization was 6.06 days and the mean follow-up period was 29.97 months. Recurrences were mentioned in 10 of 96 patients with available data. No deaths owing to CFT were mentioned in the literature.CFT should be included in the differential diagnosis of enlarging mass revealed by clinical or imaging examination either incidentally or after specific acute or chronic symptomatology.

Mesenchymal tumours of the mediastinum--part I

The mediastinum is an anatomically defined space in which organs and major blood vessels reside with surrounding soft tissue elements. The thymus is an important organ in the mediastinum, and many of the masses encountered in the mediastinum are related to this organ. Most neoplasms diagnosed in the mediastinum are epithelial tumours (thymomas and thymic carcinomas), lymphomas or germ cell tumours. In contrast, soft tissue tumours of the mediastinum are rare. In 1963, Pachter and Lattes systematically reviewed soft tissue pathology of the mediastinum, covering the hitherto described [2, 226, 227] In this review, based on the 2013 WHO classification of soft tissue tumours and the 2015 WHO classification of tumours of the lung, pleura, thymus and heart, we provide an updated overview of mesenchymal tumours that may be encountered in the mediastinum.

Multifocal calcifying fibrous tumor at six sites in one patient: a case report

Calcifying fibrous tumors (CFT) are rare benign tumors. They usually affect children and young adults and the incidence is equal in males and females. The usual clinical presentation is that of a painless mass. A computed tomography scan typically reveals a well-demarcated calcified lesion. CFT usually presents as a solitary mass and the commonest sites of occurrence are in soft tissues, the pleura, or the peritoneum. Multifocal occurrences at the same site have also been reported. The first case of CFT was reported in 1988. We present a rare case of multiple calcifying fibrous tumors at multiple sites in the same patient. To the best of our knowledge, this is the first ever reported case of multifocal CFT atsix different anatomical sites in one patient.

Calcifying fibrous tumor presenting as rectal submucosal tumor: first case reported in rectum

Calcifying fibrous tumor (CFT) is a recently recognized rare benign lesion characterized by dense hyalinized collagenous tissue with interspersed spindle cells and a lymphoplasmocytic infiltrate. Calcification is the hallmark of CFT and may present in the form of psammomatous bodies or dystrophic calcifications. CFT of the intestinal tract is uncommon and rectal CFT has never been reported. Recently, we experienced a case of CFT found in the rectum of a 36-year-old man. In this study, we described the characteristic histopathological findings with a review of the relevant literature. Although CFT of the intestinal tract as an intrinsic visceral lesion is unusual and clinically unexpected, CFT should be considered in the differential diagnosis of rectal submucosal tumor.

Multifocal peritoneal calcifying fibrous tumour: incidental finding at cholecystectomy

Calcifying fibrous tumour (CFT) is a benign tumour of elusive aetiology and a potential for local recurrence. Despite its peculiar histological characteristics it can still be confused with interrelated differential diagnosis like inflammatory myofibroblastic tumour (IMT) or solitary fibrous tumours. The clinical differential diagnosis is however much wider. To date seven cases of multiple peritoneal CFTs are on record. The authors present a case discovered incidentally during laparoscopic cholecystectomy, with no previous history and no radiological diagnosis achieved despite having undergone magnetic resonance cholangiopancreatography (MRCP) and normal routine perioperative investigation. The patient is disease-free 12 months after diagnosis. The case report is followed by a detailed literature review.

Imaging findings of calcifying fibrous tumour of the liver

Calcifying fibrous tumour (CFT) is a recently recognised rare benign lesion characterised by dense hyalinised collagenous tissue, psammomatous or dystrophic calcifications and a lymphoplasmacytic infiltrate. The usual locations of the lesion are the soft tissues of the extremities, but rarely it occurs in the abdomen. Recently, we experienced a case of CFT found in the liver of a 29-year-old woman. Here, we describe the characteristic radiological and histopathological findings, along with a review of the relevant literature.

Calcifying fibrous pseudotumor of the esophagus

Calcifying fibrous pseudotumor is an uncommon lesion and has recently been recognized as a distinctive fibrous lesion. Esophageal calcifying fibrous pseudotumor is extremely rare and, to the best of our knowledge, has never been reported before. A 54-year-old woman underwent upper gastrointestinal endoscopy and endoscopic ultrasound because of intermittent dysphagia. The results showed 1 isoechoic esophageal submucosal tumor over the deep mucosa and submucosal layers, with calcifications inside. The patient underwent tumor excision, and the diagnosis was confirmed by pathological features, with abundant collagen, calcification and inflammatory cell infiltration. She received regular follow-up at the clinic and no evidence of tumor recurrence was found.

Pseudoneoplasms of the Nervous System

Context.—Pseudoneoplasms of the nervous system vary greatly in nature. Ranging from inflammatory to autoimmune, infectious, malformative, reactive, degenerative, and radiation induced, they all mimic true tumors. Thus, they have the potential to mislead clinicians, radiologists, and pathologists alike. Their clinical and/or neuroimaging and histologic features are readily misinterpreted as tumor. Knowledge of the pitfalls is essential to avoid mismanagement, specifically overtreatment. In such instances, pathologists must take the entire clinical picture into consideration, acquainting themselves with presenting symptoms, physical findings, and neuroimaging.

Objective.—To present 10 examples of pseudoneoplasms of the nervous system, analyze the basis for their mimicry, and discuss their differential diagnosis.

Data Sources.—Review of the pertinent literature related to pseudoneoplasms of the nervous system and review of the consultation files of one of the authors (B.W.S.).

Conclusions.—The identification of tumor mimics may be difficult under the best of circumstances, and maintaining a broad differential diagnosis as well as application of a variety of immunocytochemical and occasionally ultrastructural and/or molecular genetic methods is essential to arrive at a correct diagnosis.

PULMONARY VASCULAR REACTIVITY OF SPONTANEOUSLY HYPERTENSIVE RATS IS EXACERBATED IN RESPONSE TO THE CENTRAL ADMINISTRATION OF EXOGENOUS NITRIC OXIDE

1. Centrally, nitric oxide (NO) is a sympathoinhibitory substance. Spontaneously hypertensive rats (SHR) have an impaired central nitroxidergic system and, consequently, NO-mediated decrease in sympathetic activity is exacerbated in SHR compared with Wistar-Kyoto (WKY) rats. We have demonstrated previously that acute hypoxic pulmonary vasoconstriction (HPV) is enhanced by central NO administration. Therefore, in the present study, we hypothesized that accentuation of the HPV by NO would be exacerbated in SHR compared with WKY rats. 2. Mean pulmonary arterial pressure, systemic mean arterial blood pressure, cardiac output and heart rate were measured in pentobarbitone-anaesthetized, artificially ventilated, male SHR and WKY rats. The brief, transient response to a bolus intracerebroventricular (i.c.v.) dose of N(G)-nitro-L-arginine methyl ester (L-NAME; 150 microg in 10 microL) was recorded in all rats. Upon recovery, rats were exposed to acute hypoxia (10% O(2) for 4 min) before and after the i.c.v. administration of the NO donor 3-[4-morpholinyl]-sydnonimine-hydrochloride (SIN-1; 100 microg in 10 microL). 3. In WKY rats, central inhibition of NO synthesis by L-NAME caused a mild increase in tonic pulmonary vascular tone and induced a large systemic pressor response. These responses were not observed in SHR. In contrast, SIN-1 failed to alter tonic pulmonary vascular tone, although it enhanced the HPV in WKY rats and, significantly more so, in SHR. 4. These results confirm that accentuation of the HPV by NO is exacerbated in SHR compared with WKY rats. The mechanism(s) by which the HPV is accentuated by central NO remains to be fully elucidated, but is likely to be associated with the sympathoinhibitory effects of NO and, if so, supports the idea that the nitroxidergic system of the SHR is impaired. Further electrophysiological studies are essential to confirm these assumptions.

Calcifying fibrous pseudotumor of the myocardium

Calcifying fibrous pseudotumor is an uncommon tumor first described in 1988 as a childhood fibrous tumor with psammoma bodies. The typical pathological findings are those of a densely collagenized fibrous tumor with psammomatous and dystrophic calcification accompanied by a lymphoplasmacytic infiltrate. To date these tumors are reported in subcutaneous and deep soft tissues of the extremities and trunk, groin, scrotum, pleura, mediastinum, paratracheal region, peritoneum, neck, mesentery, omentum, serosa, lung, bone, and gallbladder. We describe a 17-year-old girl with a myocardial calcifying fibrous tumor, and we review the English literature.

Exogenous nitric oxide centrally enhances pulmonary reactivity in the normal and hypertensive rat

1. Chronic hypoxia causes sustained pulmonary hypertension and, although impairment of the pulmonary endothelial nitric oxide (NO) pathway has been implicated, no study has described the central role of NO in modulating pulmonary vascular tone and reactivity. Centrally, NO inhibits sympathetic outflow, so we hypothesised that central NO would modulate pulmonary vascular tone and its reactivity to acute hypoxia, especially in the hypertensive state. 2. Male adult Sprague-Dawley rats were exposed to normoxia (N) or chronic hypoxia (CH; 12% O2) for 14 days. Mean pulmonary arterial pressure (MPAP), systemic mean arterial blood pressure (MABP), cardiac output and heart rate were then measured in pentobarbitone-anaesthetized, artificially ventilated rats. The N and CH rats were exposed to acute hypoxia (10% O2 for 4 min) after the intracerebroventricular (i.c.v.) administration of artificial cerebrospinal fluid (control) and then again after either i.c.v. NG-nitro-L-arginine methyl ester (L-NAME; 150 microg in 10 microL) or 3-morpholino-sydnonimine hydrochloride (SIN-1; 100 microg in 10 microL). 3. Chronic hypoxia caused pulmonary hypertension (MPAP 20+/-1 vs 30+/-1 mmHg in N and CH rats, respectively) and attenuated acute hypoxic pulmonary vasoconstriction (HPV). Central inhibition of NO synthesis (by l-NAME) did not alter baseline MPAP or the acute HPV in either N or CH rats, but it did elevate MABP. The NO donor SIN-1 did not alter baseline MPAP, but it did enhance (N rats) or restore (CH rats) the HPV and decreased MABP. 4. The results of the present study indicate that central NO has a limited role in the tonic modulation of MPAP during normoxia and after chronic hypoxia. However, the acute HPV seems to be enhanced by exogenous NO.

Multiple calcifying fibrous tumors of the pleura

Calcifying fibrous tumor (CFT) is a rare lesion characterized histologically by hypocellular hyalinized collagenous tissue with psammomatous and/or dystrophic calcifications and patchy lymphoplasmacytic infiltrates. CFT usually occurs in the somatic soft tissue of children and young adults but is rarely found in the pleura. We describe here an unusual case of multiple small CFTs in the right mediastinal pleura of a 54-year-old man who had a history of renal cell carcinoma. Suspecting pulmonary and pleural metastases, we performed wedge resection of the right middle lobe and local excision of two nodules in the right pleura. Light microscopy revealed metastatic lesions of renal cell carcinoma in the resected wedge. The pleural nodules were well circumscribed and composed of hypocellular, dense, hyalinized, collagenous tissue with scant lymphoplasmacytic infiltration and characteristic psammoma bodies. Immunohistochemical staining revealed that most spindle cells were positive for vimentin, CD34 and factor XIIIa, and negative for epithelial membrane antigen, keratin, smooth-muscle actin, desmin, S-100 protein and anaplastic lymphoma kinase. We made a histological diagnosis of CFT of the pleura, and the patient remains well 6 months after the wedge resection.

Familial peritoneal multifocal calcifying fibrous tumor

Calcifying fibrous tumor (CFT) is usually solitary, involving the soft tissue, pleura, or peritoneum. The cause and pathogenesis are unclear. Cases with multifocal lesions are rare, and a familial occurrence has not been reported. Herein, a family in which 2 sisters developed multifocal peritoneal CFT is described. The sisters each had abdominal pain, and each was found at laparotomy to have multiple nodular lesions on the mesenteric, omental, and small bowel serosal surfaces. Many lesions were composed of collagenous, paucicellular, fibrous tissue with psammomatous or dystrophic calcification, consistent with CFT. Some lesions were composed of more cellular spindle-celled tissue resembling inflammatory myofibroblastic tumors. Both patients were alive and well 19 and 17 years after diagnosis, respectively. One other sibling and 2 children of one of the sisters were speculated to have the same disorder, based on clinical findings. This report suggests that there may be genetic susceptibility to CFT, although chance and common environmental etiologic factors cannot be excluded.

Calcifying fibrous 'pseudotumor': clinicopathologic study of 15 cases and analysis of its relationship to inflammatory myofibroblastic tumor

Calcifying fibrous pseudotumor (CFP) has been postulated to be a "late" stage of inflammatory myofibroblastic tumor (IMT). We analyzed 15 cases (8 females and 7 males; aged 1 to 65 years). The anatomic distribution was wide, including 3 cases each in neck, mesentery/omentum, and GI tract and 2 cases each in mediastinum and paratesticular sites. Follow-up information was available in 10 patients (range 4 to 228 months). Local recurrence occurred in 3 patients and was repeated in 2. Tumor size ranged from 0.6 to 25 cm. Lesions were well-circumscribed hypocellular spindle cell proliferations with dense stromal collagen, a lymphoplasmacytic infiltrate, and stromal calcifications. Features of conventional IMT were not seen. Immunostaining showed CD34 positivity in most cases as well as rare cells positive for smooth muscle actin and desmin, and consistent negativity for ALK-1 and S-100 protein. These findings suggest that CFP is a distinctive benign mesenchymal neoplasm with a low risk for recurrence and, therefore, best labelled as "calcifying fibrous tumor." There is no convincing evidence to support an association between CFP and IMT.

Calcifying fibrous pseudotumor of mesentery presenting with acute peritonitis: case report with immunohistochemical study and review of literature

Calcifying fibrous pseudotumor (CFP) is a benign soft tissue lesion composed of thick collagen bundles, scattered fibroblasts, and psammomatous and dystrophic calcifications, located most commonly in the extremities and trunk of children and young adults. The present case in a 36-year-old woman is to the best of our knowledge the first report of a large CFP confined to the mesentery, which, because of torsion, led to acute peritonitis and emergency laparotomy. The typical histologic features were accompanied by a prominent myofibroblastic proliferation along with inflammatory response at the periphery of the lesion. The spindle cells of the lesion were positive for vimentin and focally for CD34 and smooth-muscle actin. Review of the literature and discussion of differential diagnosis in this report focuses on abdominal CFP and other intraabdominal soft tissue lesions, some of which may be precursors of CFP. Int J Surg Pathol 9(3):249-253, 2001

Intraosseous calcifying pseudotumor of the axis: a case report

STUDY DESIGN

A case report and review of the literature.

OBJECTIVE

To present the first case of intraosseous calcifying pseudotumor arising from the axis.

SUMMARY OF BACKGROUND DATA

Calcifying pseudotumor is a very rare disease. Only 24 cases have been previously reported.

METHODS

A case of calcifying pseudotumor involving the body, dens, and laminae of the axis in a 60-year-old male patient was managed with total laminectomy of the axis and instrumented occipitocervical fusion, followed by the curettage of the body and dens of the axis and autogenous iliac bone graft. Medical records, imaging studies, microscopic findings, and related literature are reviewed.

RESULTS

Microscopic examination showed amorphous, basophilic, and chondroid calcifying masses surrounded with palisading histiocytes and foreign body-type giant cells. The findings were consistent with those of calcifying pseudotumors previously reported in other sites of the body. At 24 months after operation, a significant reduction of neck pain was achieved. But there was evidence of local recurrence of the lesion in the body and dens of the axis with a local progression of the preexisting lesion in the facet joints.

CONCLUSION

This is the first report of intraosseous calcifying pseudotumor arising from the axis.

Calcifying fibrous pseudotumor: an ultrastructural study

To clarify the pathogenesis of calcification in calcifying fibrous pseudotumor (CFT), the lesion arising in the chest wall of a 16-month-old boy was ultrastructurally investigated. Fibroblasts were surrounded by large amounts of collagen fibrils. The dystrophic and psammomatous calcifications were observed as electron-dense amorphous masses and laminated bodies, respectively, within the cytoplasm of fibroblasts and in the collagenous stroma. The degeneration of cytoplasm seemed to be an initial event of intracytoplasmic calcification. Extracellular calcified substances often abutted to fibroblasts. Fibroblasts may play an important role in both intracellular and extracellular calcifications of CFT.

Is calcifying fibrous pseudotumor a late sclerosing stage of inflammatory myofibroblastic tumor?

Calcifying fibrous pseudotumor is a recently described distinctive lesion, characterized by the presence of abundant hyalinized collagen with psammomatous or dystrophic calcifications and a lymphoplasmacytic infiltrate. The cause and pathogenesis are unclear, but a possible relationship with other pseudotumors, like nodular fasciitis or inflammatory myofibroblastic tumor, has been proposed by some authors. However, cases with overlapping histologic features have not been reported. A 17-year-old girl with multiple peritoneal calcifying fibrous pseudotumors and inflammatory myofibroblastic tumors (inflammatory pseudotumors) is described. Some multinodular lesions showed calcifying fibrous pseudotumors next to inflammatory myofibroblastic tumors. Transitional stages between calcifying fibrous pseudotumor and inflammatory myofibroblastic tumor were also present. This case clearly illustrates a histogenetic relationship between calcifying fibrous pseudotumor and inflammatory myofibroblastic tumor, and it suggests that calcifying fibrous pseudotumor is a late sclerosing stage of inflammatory myofibroblastic tumor, at least in some cases.