Intended for healthcare professionals

Feature Christmas 2011: Food for Thought

What Three Wise Men have to say about diagnosis

BMJ 2011; 343 doi: (Published 20 December 2011) Cite this as: BMJ 2011;343:d7769
  1. Navin Mani, specialty registrar, otolaryngology—head and neck surgery1,
  2. Nick Slevin, consultant, clinical oncology2,
  3. Andrew Hudson, specialty registrar, clinical oncology2
  1. 1Department of Head and Neck Surgical Oncology, Christie Hospital, Manchester M20 4BX, UK
  2. 2Department of Head and Neck Clinical Oncology, Christie Hospital, Manchester
  1. Correspondence to: N Mani navmani{at}

Navin Mani and colleagues examine Occam’s razor, Hickam’s dictum, and Crabtree’s bludgeon

Most clinicians will be familiar with Occam’s razor, a guiding principle that is interpreted as “the simplest explanation is to be preferred.” In relation to medical diagnosis this is taken to mean that when a patient has multiple symptoms and signs, a single diagnosis should be sought that accounts for all the clinical features rather than attributing a different diagnosis to each.

To what extent should we rely on Occam’s wisdom? All clinicians can recall patients who have not conformed to this principle, and over reliance on it has the potential for misdiagnosis. Accurate diagnosis underpins good clinical practice; figures suggest that rates of diagnostic errors in the emergency department setting are as high as 10-15%1 and that misdiagnosis is responsible for around 10% of adverse events in hospitals.2 With this in mind, we present examples for and against the use of Occam’s razor from our area of interest: head and neck oncology, the management of which provides a good template to study these diagnostic dilemmas. Most patients undergo imaging of distant sites at diagnosis, and spread to the regional lymph nodes usually occurs in a predictable pattern before distant metastases. We also examine the views of other “wise men” who have proposed principles that caution against over reliance on Occam.

Occam: “entities must not be multiplied beyond necessity”

A 60 year old female smoker presented with haemoptysis. Chest radiography showed an opacity in the middle lobe of her right lung. She underwent lobectomy. Histology showed adenocarcinoma with clear resection margins (stage T2 N0 M0). No adjuvant therapy was given. One year later she presented with a left tonsillar mass and left cervical lympadenopathy (fig 1). Biopsy of the left tonsil was reported as adenocarcinoma (stage T2 N2b M0) with similar histological features …

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