1
|
Shibahara Y, Krzyzanowska M, Vajpeyi R. Appendiceal Well-Differentiated Neuroendocrine Tumors: A Single-Center Experience and New Insights into the Effective Use of Immunohistochemistry. Int J Surg Pathol 2022; 31:252-259. [PMID: 35491663 PMCID: PMC10101181 DOI: 10.1177/10668969221095172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background. Appendiceal well-differentiated neuroendocrine tumor is the most common histological type of appendiceal tumor. The majority of tumors are found incidentally at the tip of the appendix, with few exceptions. Due to its primarily indolent nature, this entity presents unique pathological challenges, particularly in the appropriate use of immunohistochemistry which this study aims to clarify. Patients and methods. Patients diagnosed at University Health Network (Canada) between 2005–2019 were selected and reviewed. Results. We identified 70 patients and sex distribution was female 60%; median age 36.5 years. Among them, 63 patients underwent appendectomy, and seven had initial right hemicolectomy for non-appendix lesions. Mean tumor size was 5.0 mm. Tumor extent was submucosa (15%); muscularis propria (34%); subserosa or mesoappendix (42%); visceral peritoneum (8%). All were clinically non-functional and negative for nodal and distant metastasis. Ninety percent of tumors were WHO Grade 1; 10% were WHO Grade 2. Immunohistochemically, an average of six stains were performed per patient. Nearly all tumors were positive for chromogranin A, synaptophysin, CAM5.2, and CDX2. MIB-1 staining was < 3% in 58/63 tumors. Other immunohistochemical stainings performed were hormonal markers (serotonin, glucagon, pancreatic peptide, peptide YY). Subsequent right hemicolectomy was performed on five patients. All were followed up (median 4 years 8 months), and all were alive without recurrence except for one patient who died of another comorbidity. Conclusion. Tumors that are small, localized, and of low grade can be reasonably exempt from an extensive immunohistochemical panel in the absence of non-typical clinical and morphological features.
Collapse
Affiliation(s)
- Yukiko Shibahara
- Anatomical Pathology, Laboratory Medicine Program, University Health Network, Toronto, Canada
- Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
- Department of Pathology, Kitasato University, Sagamihara, Japan
| | - Monika Krzyzanowska
- Cancer Quality Lab (CQuaL), Princess Margaret Cancer Centre, University Health Network, Toronto, Canada
- Management and Evaluation, Institute of Health Policy, University of Toronto, Toronto, Canada
- Department of Medicine, University Health Network, Toronto, Canada
| | - Rajkumar Vajpeyi
- Anatomical Pathology, Laboratory Medicine Program, University Health Network, Toronto, Canada
- Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Canada
| |
Collapse
|