|Year : 2012 | Volume
| Issue : 2 | Page : 317-319
Inflammatory myofibroblastic tumor appendix with concomitant mucosal dysplasia, simulating pseudomyxoma on preoperative aspiration cytology
Kaushik Majumdar1, Puja Sakhuja1, Sukhpreet Kaur2, Archana Rastogi3, Ranjana Gondal1, Anil Agarwal4
1 Department of Pathology, G B Pant Hospital, Jawaharlal Nehru Marg, New Delhi, India
2 Department of Pathology, Bhopal Memorial Hospital and Research centre, Bhopal, India
3 Department of Pathology, Institute of Liver and Biliary Sciences, Vasant Kunj, New Delhi, India
4 Department of Gastrointestinal Surgery, G B Pant Hospital, Jawaharlal Nehru Marg, New Delhi, India
|Date of Web Publication||26-Jul-2012|
Department of Pathology, Academic Block, G B Pant Hospital, Jawaharlal Nehru Marg, New Delhi -110002
Inflammatory myofibroblastic tumor (IMT) has been described as a pseudosarcomatous proliferation of spindled myofibroblasts admixed with lymphoplasmacytic cells. The various terminologies like inflammatory pseudotumor, plasma cell granuloma, and inflammatory myofibrohistiocytic proliferation, used to describe this entity, highlight the controversial etiopathogenesis of this relatively indolent neoplasm. IMT has now been described in different anatomic locations. However, cases occurring in the gastrointestinal tract are rare with very few cases described in the appendix. We present a case of inflammatory myofibroblastic tumor appendix with mucosal dysplasia in a 41-year-old male, presenting with abdominal pain and lump in the right iliac fossa. Aspiration cytology yielded few atypical epithelial cells and spindle cells in a mucinous background, suggesting the possibility of pseudomyxoma peritonei. Awareness of IMT appendix with rare presence of mucosal dysplasia may help in preventing overzealous resection, especially in situations that on preoperative evaluation may suggest malignancy.
Keywords: Appendix, dysplasia, inflammatory myofibroblastic tumor, pseudomyxoma
|How to cite this article:|
Majumdar K, Sakhuja P, Kaur S, Rastogi A, Gondal R, Agarwal A. Inflammatory myofibroblastic tumor appendix with concomitant mucosal dysplasia, simulating pseudomyxoma on preoperative aspiration cytology. J Can Res Ther 2012;8:317-9
|How to cite this URL:|
Majumdar K, Sakhuja P, Kaur S, Rastogi A, Gondal R, Agarwal A. Inflammatory myofibroblastic tumor appendix with concomitant mucosal dysplasia, simulating pseudomyxoma on preoperative aspiration cytology. J Can Res Ther [serial online] 2012 [cited 2013 Jun 19];8:317-9. Available from: http://www.cancerjournal.net/text.asp?2012/8/2/317/99004
| > Introduction|| |
Inflammatory myofibroblastic tumor (IMT) still offers a great deal of diagnostic challenge. This is because of the lack of specific clinical or imaging signs, conclusive laboratory tests or characteristic gross appearance which can help in distinguishing this lesion from malignancy. Definitive diagnosis can be obtained on histopathologic assessment, supplemented by immunohistochemistry and molecular techniques. IMT originally was identified in the lung, followed by mesentery of small intestine, omentum, retroperitoneum of children and young adults.  However, it is now known to occur in any anatomic site, including liver, pancreas, spleen, gastrointestinal (GI) tract. IMT with concomitant mucosal dysplasia in vermiform appendix is likely to cause a preoperative or even intraoperative diagnostic confusion with malignancy, resulting in subsequent more aggressive surgery.
| > Case Report|| |
A 41-year-old male patient, chronic smoker presented with pain and gradually increasing lump in right lower abdomen for four months. This was associated with fever, anorexia and weight loss. He had no history of bleeding per rectum, hematemesis, past episode or contact with tuberculosis. The lump was 5 × 4 cm, hard, mobile, with mild tenderness on deep palpation. Ultrasound of abdomen revealed a 7 × 5 cm heterogeneous mass, predominantly hypoechoic and cystic with few isoechoic areas involving the appendix. Scanty amount of fluid collection was appreciated at the tip. The findings were suggestive of a solid cystic mass lesion or an abscess in the appendix. Contrast enhanced computed tomography (CECT) also provided almost similar impression. Barium meal follow-through revealed a 6.5 cm mass in right iliac fossa, indicating appendicular lesion. Fine needle aspiration cytology (FNAC) smears from the lump showed atypical epithelial cell clusters and few benign appearing spindle cells dispersed in a mucinous background, suggesting the possibility of pseudomyxoma peritonei [Figure 1], [inset].
|Figure 1: Gross photograph showing cut surface of the enlarged appendix with markedly thickened wall (arrow)|
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Laparotomy revealed an enlarged appendix, measuring 5.5 × 3.5 cm with markedly thickened wall, grossly appearing as an appendiceal growth. The lumen was distended by mucinous material, and small amount of mucin was also present in the adhesions surrounding the mass, small bowel mesentery and pelvis. Possibility of a disseminated mucin-secreting appendiceal tumor with mucocele was considered intraoperatively. Subsequently, the patient underwent a right hemicolectomy and ileo-transverse colon anastomosis.
Cut surface of the resected appendix showed a uniformly tan, firm to hard, thickened wall (0.8-1.2 cm) [Figure 1]. Areas of mucosal irregularity were appreciated; however, no well-defined growth was seen to arise from the mucosa into the luminal aspect. Histopathology revealed dysplasia of mucosal lining [Figure 2], with large areas of ulceration, impacted mucin, focal calcification and foreign-body giant cell reaction. None of the sections showed evidence of infiltration of dysplastic epithelium into the deeper layers, and this was further confirmed by cytokeratin immunohistochemistry. Instead, the wall of the appendix was markedly expanded by stroma rich in collagen, intense myofibroblastic proliferation, and a polymorphic infiltrate comprising of plasma cells, lymphocytes, histiocytes and few neutrophils [Figure 3]. Scattered peripherally located lymphoid aggregates were also seen. No granuloma was seen, and stain for acid fast bacilli (AFB) was negative. The spindle myofibroblastic cell population was strongly immunoreactive for smooth muscle actin
[Figure 4], desmin and negative for S-100 protein. The plasma cell population expressed both κ and λ light chains. Interspersed lymphoid follicles with prominent germinal centers, blood vessels and hyperplastic nerve bundles were also observed. A histologic diagnosis of IMT appendix with mucosal dysplasia was considered. The post operative recovery and subsequent follow-up for a period of three years were uneventful.
|Figure 2: Low power photomicrograph showing dysplasia of the mucosal epithelium of appendix (H and E stain, 40x); Inset: preoperative aspiration cytology showing few atypical cell clusters in a mucinous background (Giemsa stain, 200x magnification)|
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|Figure 3: Photomicrograph showing collagenization (lower right) and intense myofi broblastic proliferation (H and E stain, 200x); polymorphic infi ltrate comprising of plasma cells, lymphocytes, histiocytes and few neutrophils is shown in inset (H and E stain, 400x)|
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| > Discussion|| |
Initially described in 1937, IMT is histologically characterized by spindled myofibroblastic cells and an inflammatory component comprising predominantly of plasma cells, lymphocytes and histiocytes.  Pulmonary IMTs, the site where it was initially described, peak in middle adulthood. Other sites of presentation could be retroperitoneum, urinary bladder, stomach, liver, and pancreas. ,, The mean age for extrapulmonary IMTs is 9.7 years.  IMTs of the gastrointestinal tract are rare, , with only 10 confirmed cases of involvement of appendix. ,,,, Most of these reported cases of IMT appendix are adolescent or adult males.
The etiopathogenesis of IMT still remains obscure. IMT may arise due to an exaggerated or aberrant tissue response to chronic inflammatory or reparative process, which may be precipitated by trauma, surgery, recurrent infections or irritation. , Studies have shown Coxiella burnetii, Klebsiella pneumoniae, Epstien-Barr virus and Campylobacter jejuni as the possible infectious agents.  Similar ongoing infective or irritant stimuli may have resulted in the mucosal dysplasia and mucin accumulation in the present case, which contributed to the aspiration cytologic impression of pseudomyxoma peritonei. We came across 10 cases of appendiceal IMT during our literature search, and none of them had any evidence of mucosal dysplasia, malignancy, or recurrence. To our knowledge, this case may be first appendiceal IMT being described with concomitant mucosal dysplasia.
Clinical manifestations of IMT also usually relate to the organ concerned.  Hence appendiceal IMT may present with features of acute or recurrent appendicitis. , Macroscopically it appears as a firm, white or tan lesion mostly involving the wall, with a whorled fleshy, fibrotic or myxoid cut surface. The surface may show a variegated appearance due to areas of necrosis, hemorrhage, or calcification in a minority of cases. ,, In this patient, the appendix was grossly enlarged with markedly thickened wall and homogenous grey white firm cut surface, along with small amount of mucin in the intraluminal aspect and peri-appendiceal adhesions.
A correct preoperative diagnosis of IMT appendix through imaging or image-guided aspiration cytology is hence difficult, but awareness of its existence might prevent extensive surgical resections. These lesions are known to follow a relatively benign clinical course, and appendicectomy with subsequent histological confirmation should be sufficient for most patients.  Nonetheless, rare cases of IMT with local recurrence, aggressive clinical course, multifocality and metastasis have been reported. , Predictors of aggressive behavior include cellular atypia, ganglion like cells, necrosis, nucleolar prominence, atypical or increased mitotic figures, expression of p53 and aneuploidy.  None of these histological parameters were observed in our case, and the lesion was also negative for immunohistochemical expression of p53.
The spindle cells in majority of cases are positive for vimentin, smooth muscle actin and/or muscle-specific actin, supporting their myofibroblastic profile. There is no reactivity for myogenin, myoglobin, CD34, CD117, or S100. Reactivity for desmin and cytokeratin may be seen. The plasma cells label for both κ and λ light chains, proving their reactive, polyclonal nature.  These immunohistochemical features distinguish IMT from inflammatory fibroid polyps, gastrointestinal stromal tumors, smooth muscle tumors, sclerosing mesenteritis, peripheral nerve sheath tumors, lymphoma and other malignant tumors. Inflammatory fibrous polyps are benign reactive submucosal polypoidal lesions, occurring commonly in the stomach and ileum and comprising of stellate shaped cells in a myxoid stroma, along with blood vessels and eosinophil rich mixed inflammatory infiltrate. Leiomyosarcomas have a more regular fascicular pattern, with plump cigar shaped nuclei and lack of significant inflammatory cell infiltrate. Gastrointestinal stromal tumor (GIST), peripheral nerve sheath tumor and solitary fibrous tumor can be excluded with the help of immunohistochemistry for c-Kit (CD 117), S100, and CD34, respectively. GISTs are, however, positive for both CD 117 and CD34.
To conclude, appendiceal IMT can be a rare outcome of a long standing chronic inflammatory process. Incidental coexistence of mucosal dysplasia and mucin accumulation can present an additional diagnostic dilemma, simulating pseudomyxoma on preoperative image guided aspiration cytology. Appendectomy with histological confirmation and follow up should be sufficient for this relatively indolent lesion. Hence, consideration of IMT in the differential diagnosis of appendiceal lump may prevent extensive surgical resection and subsequent morbidity.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]