Reactive nodular fibrous pseudotumor: a first report of gastric localization and clinicopathologic review

Reactive Nodular Fibrous Pseudotumor Mimicking Metastatic Tumor After Gastric Cancer Operation: A Case Report and Literature Review

We describe a case of reactive nodular fibrous pseudotumor (RNFP) misdiagnosed as lymph node metastasis after gastric cancer surgery. Additionally, we summarize the clinical and imaging characteristics of RNFP, combined with the literature, to improve the understanding of preoperative diagnosis. Radiological features of RNFP are a homogenous, isodense, solid mass with gradually mild enhancement on multiphasic abdominal computed tomography (CT), and slight ¹⁸F-FDG uptake by positron emission tomography/computed tomography (PET/CT). To the best of our knowledge, this is the first report in the English literature of a case of reactive nodular fibrous pseudotumor associated with gastric cancer and its appearance on PET/CT images.

A reappraisal of sclerosing nodular and/or polypoid lesions of the gastrointestinal tract rich in IgG4-positive plasma cells

AIMS

To describe additional cases of nodular and polypoid sclerosing lesions of the gastrointestinal tract (GIT) that are associated with numerous IgG4-positive plasma cells, review the pertinent literature to ascertain the relationship with systemic IgG4-related disease, and provide a reporting framework for such lesions.

METHODS AND RESULTS

Five new cases of sclerosing polyps or nodules were collected over a 10-year period, occurring in four females and one male ranging in age from 32 years to 56 years (mean, 41.6 years). Patients were asymptomatic or had epigastric pain, and one had rectal bleeding. None had autoimmune or other obvious IgG4-related disease, and serum IgG4 levels were normal. All were solitary nodules in the stomach (two cases), ileum, caecum, and rectum. Four lesions were submucosal and one was subserosal; all were well circumscribed, composed of hyalinised, keloidal fibrous tissue with lymphoplasmacytic inflammation. Obliterative phlebitis was not seen. Lineage-specific immunomarkers were negative. In excess of 10 IgG4-positive plasma cells per high-power field were seen, and the IgG4/IgG ratios were >0.4.

CONCLUSIONS

Very few IgG4-related lesions in the tubular GIT are associated with disease at other sites and/or elevated serum IgG4 levels. The majority may represent a lesion in the spectrum of IgG4-related disease. The use of the term 'IgG4-positive nodule or polyp with probable histological features of IgG4-related disease' is advocated for nodular and/or polypoid lesions in the GIT with ≥10 IgG4-positive plasma cells in a high-power field and an IgG/IgG4 ratio of >0.4.

Gastrointestinal manifestation of immunoglobulin G4-related disease: clarification through a multicenter survey

BACKGROUND

Several reports on immunoglobulin (Ig)G4-related disease (IgG4-RD) with gastrointestinal involvement (IgG4-related gastrointestinal disease; IgG4-GID) have been published, although this entity has not been fully established clinicopathologically. Thus, we carried out a multicenter survey.

METHODS

Patients with possible IgG4-GID who underwent resection were collected. Histologic slides were reevaluated, and eight cases with diffuse lymphoplasmacytic infiltration but without numerous neutrophils, granulations or epithelioid granulomas were further analyzed.

RESULTS

Overall, the IgG4 counts (87-345/high-power field) and IgG4/IgG-positive ratio were high (44-115%). The demographic findings included advanced age among the patients (55-80 years) and male preponderance (six cases). Six lesions (five gastric, one esophageal), consisting of lymphoplasmacytic infiltration with neural involvement in the muscularis propria and/or bottom-heavy plasmacytosis in the gastric mucosa, were histologically regarded as highly suggestive of IgG4-RD. Storiform fibrosis and obliterative phlebitis were found in two cases, and the former gave rise to a 7-cm-sized inflammatory pseudotumor (IPT) in one case. Ulceration and carcinoma co-existed in three and two lesions, respectively. All the patients had other organ involvement (OOI), and serum IgG4 levels were markedly elevated (four of five patients). The remaining two cases with gastric IPTs featuring reactive nodular fibrous pseudotumor or nodular lymphoid hyperplasia were regarded as possible cases of IgG4-RD because of the histologic findings and lack of OOI.

CONCLUSIONS

IgG4-GID is found in the setting of IgG4-RD, often with ulceration or cancer. Characteristic histologic findings are observed in the muscularis propria and gastric mucosa. Cases with IPT may be heterogeneous, and there may be mimickers of IgG4-GID.

Reactive Nodular Fibrous Pseudotumor Mimicking Metastatic Gastrointestinal Stromal Tumor to Perigastric Lymph Node: A Case Report and Review of the Literature

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal lesions of the gastrointestinal tract. Many are treated surgically with or without the use of adjuvant tyrosine kinase inhibitors. Metastases to lymph nodes are infrequent. In this article, we present a case of a perigastric nodule presenting 3 years postsurgical treatment for biopsy-proven GIST, clinically suspicious for a recurrent/metastatic GIST. The patient had also received adjuvant tyrosine kinase inhibitor therapy. Microscopic sections from the perigastric lesion showed a spindle cell nodule felt initially to represent a GIST with posttherapeutic changes. Together with morphology, immunohistochemical workup supported the myofibroblastic origin of the spindle cells, consistent with a reactive nodular fibrous pseudotumor, and definitively excluded metastatic GIST. This case highlights an important diagnostic pitfall and is the first known case of a GIST preceding a reactive nodular fibrous pseudotumor.

Torsion of omental fibrous pseudotumour mimicking acute appendicitis

Unusual pathologies are occasionally found at laparoscopy when appendicitis is suspected. We present a case of strangulated inflammatory fibrous pseudotumour of the omentum presenting in a similar fashion to appendicitis. The infarcted omentum was excised, facilitating prompt resolution of symptoms.

Reactive nodular fibrous pseudotumor involving the gastrointestinal tract and mesentery: A case report and review of the literature

Reactive nodular fibrous pseudotumor (RNFP) is a tumor-like lesion that is characterized by reactive fibroblast/myofibroblast proliferation within collagenic hyalinized stroma, due to its association with injury or inflammation. The current study describes the case of a 60-year-old female with a history of abdominal surgery and abdominal pain. Upon laparoscopy, multiple nodules attached to the outer layer of the colon and mesentery were identified, and therefore, complete surgical excision was performed. Macroscopically, the nodules were well-circumscribed, firm, tan-white in color and ranged in size between 2.0–10.0 cm at the greatest dimension. Microscopically, the nodules were composed of spindle and stellate cells in a dense collagenic hyalinized background with sparse lymphocytic infiltration. Immunohistochemical analysis demonstrated positive staining for vimentin, smooth muscle actin and cluster of differentiation (CD) 117, and focally-positive keratin staining with AE1/AE3; however, no staining was observed for gastrointestinal stromal tumor 1, CD34, S-100, anaplastic lymphoma kinase or β-catenin. Therefore, it was proposed that the lesion may be most accurately described as an RNFP. The current study reports a rare case of RNFP, emphasizing its histopathological features and differential diagnoses to promote an improved and broader understanding of this poorly understood condition.

Rare case of an abdominal mass: Reactive nodular fibrous pseudotumor of the stomach encroaching on multiple abdominal organs

Reactive nodular fibrous pseudotumor (RNFP), which presents abdominal clinical manifestations and malignant radiographic results, usually requires radical resection as the treatment. However, RNFP has been recently described as an extremely rare benign post-inflammatory lesion of a reactive nature, which typically arises from the sub-serosal layer of the digestive tract or within the surrounding mesentery in association with local injury or inflammation. In addition, a postoperative diagnosis is necessary to differentiate it from the other reactive processes of the abdomen. Furthermore, RNFP shows a good prognosis without signs of recurrence or metastasis. A 16-year-old girl presented with a 3-mo history of epigastric discomfort, and auxiliary examinations suggested a malignant tumor originating from the stomach; postoperative pathology confirmed RNFP, and after a 2-year follow-up period, the patient did not display any signs of recurrence. This case highlights the importance of preoperative pathology for surgeons who may encounter similar cases.

Torsed reactive nodular fibrous pseudotumor in an adolescent: case report and review of the literature

We describe a case of a 13-year-old girl presenting with acute abdominal pain and imaging suggesting acute appendicitis. Upon laparoscopy, she was found to have a mass attached to the jejunum that had torsed upon its blood supply. On histopathologic studies, the mass was determined to be a reactive nodular fibrous pseudotumor. This lesion is a benign neoplasm that may arise from the gastrointestinal tract and has only been recently described in the literature. Our case is unique because it is the first report of reactive nodular fibrous pseudotumor presenting as a torsed polypoid lesion and the first arising in an adolescent.

Sclerosing nodular lesions of the gastrointestinal tract containing large numbers of IgG4 plasma cells. Pathology. 2011;43:31-35. [PMID: 21240062 DOI: 10.1097/pat.0b013e328340e450]

BACKGROUND

Hyalinised fibrous nodules have been encountered within the gastrointestinal tract (GIT) and been labelled as reactive nodular fibrous tumours. Several have a history of abdominal surgery and/or sepsis that acts as a precipitating cause for the fibrosis. Recently, much attention has been focused on IgG4 related fibrosing lesions that are typically associated with a high population of IgG4 positive plasma cells and tissue fibrosis. There may be attendant elevated serum IgG4 levels and associated autoimmune disease.

METHODS

We present four patients with well-circumscribed fibrous nodular lesions occurring in the GIT. Tissue was formalin fixed after microwave antigen retrieval and H&E stains and immunohistochemistry were performed. IgG4/IgG ratios were calculated from the three high power fields containing the densest concentration of positive plasma cells.

RESULTS

The patients were two females (45 and 56 years) and two males (47 and 60 years) who presented with gastric (2 cases), caecal and sigmoid flexure involvement. One case had four lesions while the other three cases were solitary nodules. Two patients had coexistent autoimmune disease. All lesions were nodular and composed of paucicellular, hyalinised fibrous tissue associated with chronic inflammation. In all lesions the plasma cell population was strongly IgG4 positive.

CONCLUSIONS

This paper describes unique, well-circumscribed sclerosing nodules containing IgG4 positive plasma cells within the bowel wall that may cause mucosal polypoid lesions. It is possible that these lesions may be related to the spectrum of IgG4 related sclerosing disease or belong to a separate subset of inflammatory reactive conditions that are rich in IgG4 plasma cells.