A 38-year-old woman comes to the hospital with 4 hours of abdominal pain, nausea, and vomiting. Her pain started in the periumbilical area and is now localized to the right lower quadrant. Temperature is 38.3 C (101 F). On examination, the patient has right lower quadrant tenderness with guarding. An appendectomy is performed, and light microscopy of the appendix shows infiltrating neutrophils in the muscularis propria, consistent with the diagnosis of acute appendicitis. Further evaluation reveals abnormal islands of small cells, as shown in the image below. These cells are most likely derived from which of the following sources?

Question

A 38-year-old woman comes to the hospital with 4 hours of abdominal pain, nausea, and vomiting.  Her pain started in the periumbilical area and is now localized to the right lower quadrant.  Temperature is 38.3 C (101 F).  On examination, the patient has right lower quadrant tenderness with guarding.  An appendectomy is performed, and light microscopy of the appendix shows infiltrating neutrophils in the muscularis propria, consistent with the diagnosis of acute appendicitis.  Further evaluation reveals abnormal islands of small cells, as shown in the image below.  These cells are most likely derived from which of the following sources?

Quizplus · Accepted Answer

The image shows the typical microscopic appearance of a carcinoid tumor. Note the uniformity in shape and size of the cells that comprise the islands. Trabeculae, glands, strands, or sheets of cells may also be formed. Tumor cells have an eosinophilic cytoplasm and oval-to-round stippled nuclei. On electron microscopy, multiple dense-core granules are seen in the cytoplasm; these contain secretory products such as vasoactive molecules (eg, serotonin, bradykinin, histamine) and hormones (eg, gastrin). Carcinoid tumors are malignant transformations of neuroendocrine cells, most commonly located in the gastrointestinal tract (eg, small intestine, rectum, appendix), followed by the bronchopulmonary system. The majority of appendiceal carcinoids have a benign clinical course. They are usually found at the tip of the appendix in asymptomatic patients who have undergone appendectomy for unrelated reasons. Tumors at the base of the appendix may cause obstruction and appendicitis. In rare cases, large tumors will metastasize to the liver, causing carcinoid syndrome (flushing, diarrhea, bronchospasm). (Choice A) Connective tissue can be a source of both benign (fibromas) and malignant (fibrosarcomas) tumors. (Choice B) Abnormal proliferation of hematopoietic cells leads to a variety of myeloid and lymphoid neoplasms. (Choice C) Intestinal epithelial cells (both absorptive and mucus-secreting) can give rise to intestinal adenocarcinomas. (Choice E) Smooth muscle cells give rise to leiomyomas and leiomyosarcomas. (Choice F) Vascular endothelial cells can be a source of benign (hemangioma), intermediate (hemangioendothelioma), and malignant (angiosarcoma) tumors. Educational objective: Carcinoid tumors are composed of islands or sheets of uniform cells with eosinophilic cytoplasm and oval-to-round stippled nuclei. These tumors are often derived from neuroendocrine cells in the gastrointestinal tract. Appendiceal carcinoids typically have a benign course but may cause appendicitis or, rarely, carcinoid syndrome (eg, with liver metastasis). __________ References: Updated population-based review of carcinoid tumors. (http://www.ncbi.nlm.nih.gov/pubmed/15213627) Carcinoid tumor of the appendix: A case report. (http://www.ncbi.nlm.nih.gov/pubmed/26137079) Gastrointestinal neuroendocrine/neuroectodermal tumors. (http://www.ncbi.nlm.nih.gov/pubmed/11993693)

A 38-Year-Old Woman Comes to the Hospital with 4 Hours