Appendiceal Mucosal Schwann Cell proliferation – Rare incidental finding in a patient of Subacute Appendicitis

Priya Subash Chandra Bose 1, Sumanth Srivatsan2, Swami Nathan Sambandam 3

1Senior consultant, Department of Histopathology. Kauvery Hospital, Alwarpet, Chennai

2Associate consultant, General surgery HPB and colorectal surgery, Kauvery Hospital, Alwarpet, Chennai

3Senior consultant & Head, Liver, Multiorgan Transplant Surgery & Hepato Pancraeto biliary surgery, Kauvery Hospital, Alwarpet, Chennai

Case Presentation

A 47-year-old man presented to the outpatient department with symptoms of right iliac fossa pain, fever and mild vomiting. Clinical diagnosis of acute appendicitis was made, which was confirmed by an ultrasound abdomen. The patient underwent laparoscopic appendectomy and the specimen was sent for routine histopathological examination.

Pathologic findings

We received an appendix measuring 3cm in length and 1 cm in diameter. External surface was gray tan and unremarkable. Cut surface showed occluded lumen. No specific gross lesions were identified.

Microscopic examination of the sections from appendix showed markedly narrowed lumen with surrounding mucosa lined by columnar cells and goblet cells.  Mucosal and transmural inflammation, consistent with subacute appendicitis was present. The muscular layer was hypertrophied, as well. In-addition the mucosa showed an ill-defined proliferation of bland spindle cells with moderate eosinophilic cytoplasm, indistinct cell borders and uniform oval to elongated bland nuclei. The proliferation was confined to the mucosa.

Immunohistochemistry examination with antibody to S100 protein was performed. The spindle cells were immunoreactive exhibiting a diffuse and strong positivity, thus confirming them as Schwann cells. Thus, a provisional diagnosis of incidental Mucosal Schwann cell proliferation was considered. Following which, the entire specimen was submitted for microscopic examination, but did not reveal any evidence of diverticula, dysplasia and malignancy. Hence, a final diagnosis of Subacute appendicitis with associated Appendiceal mucosal Schwann cell proliferation was offered.

Discussion

Appendiceal neural proliferation has been described in the submucosa and mucosa of the appendix.1 According to the location and growth pattern of this proliferation, they are classified as central obliterative type, nodular type, and intramucosal type. Of these various proliferations, the intramucosal proliferation is less common. 2 The lesional neural cells were uniformly S-100 positive Schwann cells and neuroendocrine cells with neurosecretory granules2

The incidence of these neural proliferations in routine appendectomy specimens have been attributed to long-term sequelae of acute appendicitis, chronic irritation, and intermittent obstruction.

Mucosal Schwann cell proliferation was more commonly associated with cases of appendiceal diverticular disease. 3 These proliferations were noted in the adjacent normal, nonherniated appendiceal mucosa rather than within the diverticula. Hence, the proliferation is believed to be caused by a secondary response to the same chronic insult that is responsible for the formation of diverticula and not because of the presence of diverticula.3

Appendiceal diverticular disease in-turn are commonly associated with low-grade appendiceal mucinous neoplasms. 4 Sometimes the appendix proximal to the diverticula may show concomitant primary appendiceal neoplasms, including adenocarcinomas and neuroendocrine tumors. Hence it is prudent that a thorough examination of all appendix specimens with diverticula needs to be done to exclude coexisting appendicular neoplasms.5

The Schwann cell proliferation is commonly seen in diverticula and its associated neoplasms. Hence, when this proliferation is encountered during a routine pathologic examination of appendix, the pathologist needs to do thorough examination with additional sampling along with detailed microscopic evaluation to detect possible coexisting diverticular disease, which in turn may be associated with appendiceal neoplasms and epithelial dysplasia.6

Conclusion

Mucosal Schwann cell proliferation is common in appendiceal diverticular disease and may be a putative histologic marker for presence of a diverticulum. We should be aware of this association and whenever a pathologist encounters this proliferation on routine histologic sections of an appendix, further additional sampling is recommended to exclude significant appendiceal disorders including diverticula, neoplasms and dysplasia, which is critical in guiding further patient management.

References

  • Olsen BS, Holck S. Neurogenous hyperplasia leading to appendiceal obliteration: an immunohistochemical study of 237 cases. Histopathology. 1987;11:843-849.
  • Michalany J, Galindo W. Classification of neuromas of the appendix. Beitr Pathol. 1973;150:213-228.
  • Abdullgaffar B. Diverticulosis and diverticulitis of the appendix. Int J Surg Pathol. 2009;17:231-237.
  • Lamps LW, Gray GF, Dilday BR, Washington MK. The coexistence of low-grade mucinous neoplasms of the appendix and appendiceal diverticula: a possible role in the pathogenesis of pseudomyxoma peritonei. Mod Pathol. 2000;13:495-501.
  • Dupre MP, Jadavji I, Matshes E, Urbanski SJ. Diverticular disease of the vermiform appendix: a diagnostic clue to underlying appendiceal neoplasm. Hum Pathol. 2008;39:1823-1836.
  • Kallenbach K, Hijorth SV, Engel U, Schlesinger NH, Holck S. Significance of acquired diverticular disease of the vermiform appendix: a marker of regional neoplasms? J Clin Pathol. 2012;65:638-642.

Kauverian Bookshelf

Applied Medical Statistics

Journals

Kauvery Hospital
Find Doctor
Book Appointment