Correspondence
Case 24-1998: Cholesterol Atheroembolism
N Engl J Med 1998; 339:1857-1858December 17, 1998
- Article
To the Editor:
Cholesterol atheroembolism has repeatedly been featured in review articles1 and clinical pathological conference (CPC) cases in the Journal. 2 The July 30 CPC3 is a reminder that discussants eliminate cholesterol atheroembolism from their differential diagnosis only at great peril in a patient with renal failure and blue toes.2,4 In his otherwise highly informative discussion, Dr. Wong followed a probabilistic approach to reach a diagnosis. He rejected the diagnosis of cholesterol atheroembolism because “survival after cholesterol embolism is very unlikely.” Although this statement was accurate when the diagnosis could be made only at autopsy, it does not reflect the current experience. Less catastrophic episodes occur in patients with atherosclerosis either spontaneously or after invasive vascular procedures. Recent studies call attention to the fact that patients survive as long as six to eight years after cholesterol atheroembolism.5,6 Indeed, chronic renal cholesterol atheroembolism may be a cause of hyperfiltration-induced renal injury in association with the nephrotic syndrome and focal segmental glomerulosclerosis.6 Whether glomerular involvement contributed to the patient's renal failure or whether renal-artery stenosis alone was responsible cannot be determined in this instance. Although the presentation of the case included the results of extensive serologic, radiographic, and endoscopic studies, the results of urinalysis were not provided.
6 ReferencesArthur Greenberg, M.D.
Duke University Medical Center, Durham, NC 277101
Kassirer JP . Atheroembolic renal disease. N Engl J Med 1969;280:812-818
Full Text | Web of Science | Medline2
Case Records of the Massachusetts General Hospital (Case 30-1986)
Full Text | Web of Science | Medline3
Case Records of the Massachusetts General Hospital (Case 24-1998)
Full Text | Web of Science | Medline4
Cyanotic feet and renal failure in a 67-year-old manAm J Med 1983;75:509-517
CrossRef | Web of Science | Medline5
Meyrier A ,Hill GS ,Simon P . Ischemic renal diseases: new insights into old entities. Kidney Int 1998;54:2-13
CrossRef | Web of Science | Medline6
Greenberg A ,Bastacky SI ,Iqbal A ,Borochovitz D ,Johnson JP . Focal segmental glomerulosclerosis associated with nephrotic syndrome in cholesterol atheroembolism: clinicopathological correlations. Am J Kidney Dis 1997;29:334-344
CrossRef | Web of Science | Medline
Author/Editor Response
Dr. Wong replies:
To the Editor: Originally conceived in the 1870s and begun at Massachusetts General Hospital in 1910 by Dr. Richard Cabot, the CPCs were designed as “an exercise in deductive reasoning” in which it was “less important to pinpoint the correct diagnosis than to present a logical and instructive analysis of the pertinent conditions involved.”1 Dr. Greenberg's comments highlight the importance of the latter. First, there are other causes of the blue toe syndrome, including thrombotic arterial occlusion, vasospastic disorders such as Raynaud's phenomenon or chronic pernio, cyanotic congenital heart disease, and miscellaneous causes such as warfarin therapy, prednisone therapy for antiphospholipid antibody, secondary syphilis, and pheochromocytoma.2 Second, cholesterol atheroembolism is not uniformly fatal, and earlier studies whose results were based principally on postmortem or surgical series may have overestimated the fatality rate because of selection bias. An updated search of the literature for the terms “blue toe syndrome” and “gastrointestinal hemorrhage” yielded two cases: one in a patient with duodenal erosions, blue toes, and renal failure and another in a patient with occult bleeding from the fundus and duodenum. Both cases were diagnosed by biopsy but resulted in death. Thus, antemortem diagnosis of cholesterol atheroembolism and gastrointestinal bleeding remains rare.
Dr. Greenberg's comments also raise the issue of the ambiguity surrounding the use of qualitative terms, such as “very unlikely,” instead of quantitative estimates by physicians among themselves and ultimately with patients. Surveyed physicians equated the term “unlikely” with a probability ranging from 0 to 95 percent.3 A 1995 study reports survival rates ranging from 19 to 38 percent for patients with cholesterol emboli.4 Similar broad ranges with respect to the use of other qualitative probabilistic words were found in a survey of patients,5 leading to the suggestion that physicians use numbers instead of words to explain the probability of an event. Perhaps preferring the inherent ambiguity, however, one in three patients would rather have physicians use only the qualitative words instead of the numerical estimates.5 Nonetheless, for educational purposes among colleagues, house staff, and students, physicians can avoid some of the uncertainty and misunderstanding by using numerical expressions, which are more precise.
Incidentally, the inadvertently omitted urinalysis revealed clear urine with a pH of 7, albumin (+), and 2 red cells, 2 white cells, a few squamous cells, and a few bacteria per high-power field.
5 ReferencesJohn B. Wong, M.D.
New England Medical Center, Boston, MA 021111
Castleman B, Dudley HR Jr. Clinicopathological conferences of the Massachusetts General Hospital: selected medical cases. Boston: Little, Brown, 1960.
2
Abdelmalek MF ,Spittell PC . 79-Year-old woman with blue toes. Mayo Clin Proc 1995;70:292-295
Web of Science | Medline3
Bryant GD ,Norman GR . Expression of probability: words and numbers. N Engl J Med 1980;302:411-411
Web of Science | Medline4
Moolenaar W ,Lamers CB . Gastrointestinal blood loss due to cholesterol crystal embolization. J Clin Gastroenterol 1995;21:220-223
CrossRef | Web of Science | Medline5
Mazur DJ ,Hickam DH . Patients' interpretations of probability terms. J Gen Intern Med 1991;6:237-240
CrossRef | Web of Science | Medline
