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General Reference ⬇

Nejm 1999;340:858

Pathophys and Cause ⬆ ⬇

Cause:Neoplasia

Pathophys:

Derived from argentaffin cells in primitive foregut (Ann IM 1972;77:53). Syndrome develops only after metastases. Symptoms related to secreted serotonin (Nejm 1967;277:1103), kallikrein (Ann IM 1969;71:763), gastrin (Nejm 1978;299:1053), histamine, dopamine, substance P, prostaglandins

Also arise in stomach w ZE or atrophic gastritis and sometimes pernicious anemia due to excessive gastrin stimulation (Nejm 1997;336:866), lungs, ovary, or pancreas (Ann IM 1972;77:53); or gi tract; those originating in appendix are rarely malignant and rarely metastasize, while those of small bowel origin become malignant (20%), many metastasize; rectal ones small and without sx

Epidemiology ⬆ ⬇

1-2/100 000/yr in US

Signs and Symptoms ⬆ ⬇

Sx:Diarrhea, wheezing/asthma, red/violaceous flushes inducible by alcohol

Si:Right-sided heart murmurs, due to right heart scarring (Nejm 2003;348:1005); fundi during flush show decreased blood flow; plastic induration of penis (Nejm 1973;289:844)

Course ⬆ ⬇

Very low-grade malignancy, can live years with mets

Complications ⬆ ⬇

r/o mastocytosis (Urticaria Pigmentosa, Mastocytosis)

Lab and Xray ⬆ ⬇

Lab:

Chem:24-h urine shows 5-HIAA (a serotonin degradation product) elevated, 86% sens, 100% specif (D. Oppenheim, 11/93) but can get false positives with glycerol guaiacolate expectorants, bananas, phenothiazines, caffeine, acetaminophen (Tylenol)

Path:Biopsy positive on silver stains

Xray:Scan with labeled octreotide (somatostatin analog) to pick up primary (12/13) and mets (Nejm 1990;323:1246)

Treatment ⬆

Rx:

Cimetidine (Tagamet) + diphenhydramine (Benadryl) (or any other H2 + H1 blocker combination) decrease flush sx (Nejm 1979;300:236)

Somatostatin analog (octreotide) sc q 8-12 h controls flushing and diarrhea sx (Med Let 1989;31:66; Nejm 1986;315:663) by blocking somatostatin receptors on the tumor (Nejm 1990;323:1246), somatostatin LAR preparation if short-acting effective, typical dosage 100-600 µgm/d in 2-4 doses, up to 1500 µgm/d

Streptozocin and 5-FU or cyclophosphamide for malignant types

Surgical of appendiceal types, simple appendectomy if <2 cm or elderly; right colectomy if >2 cm irrespective of degree of wall or other invasion (Nejm 1987;317:1699)

of metastatic disease, hepatic artery occlusion followed by 2-drug chemotherapy (Ann IM 1994;120:302); perhaps liver transplant