Muller v King's College Hospital NHS Foundation Trust

In a pure diagnosis case, where a doctor reports a condition without making a treatment decision, the court must determine objectively whether the diagnosis fell below the standard of reasonable skill and care. Opposing expert opinions cannot both determine the legal standard. The court may prefer one opinion, but must respect the Bolitho v City and Hackney Health Authority exception: an expert opinion cannot prevail if its reasoning is logically indefensible or applies the wrong legal test. Rarity, hindsight and the possibility of an understandable error remain relevant to whether negligence is proved. Causation and quantum are determined on the balance of probabilities, with broad estimates permitted where loss cannot be calculated precisely.

The claimant alleged that an employee of the defendant NHS Foundation Trust negligently reported a punch biopsy from his foot as an ulcer in November 2011, when it showed an acro-lentiginous malignant melanoma. The melanoma was diagnosed after a later excision in July 2012, followed by further surgery.

The issues were whether the histopathological report was negligent, whether the cancer had already spread to the lymph nodes in November 2011, whether the claimant would have undergone a sentinel lymph node biopsy at that time, and what loss was caused by the delayed diagnosis.

1. Liability. The claim succeeded on breach of duty. The court distinguished a pure diagnosis case from a pure treatment case. The former involves an objectively right or wrong diagnostic report, without a clinical choice between competing treatments or procedures. The ordinary Bolam v Friern Barnet Hospital Management Committee approach is principally directed to treatment decisions involving clinical judgment and the weighing of risks and benefits.

2. The court treated Penney v East Kent Health Authority as the closest authority. It was entitled to determine what a reasonably competent histopathologist should have recognised on the slides. However, under the existing law, it had to consider the Bolitho v City and Hackney Health Authority qualification. An expert opinion could be rejected where it was logically indefensible or proceeded from a legally impermissible standard.

3. The slides contained visible features that were inconsistent with a benign ulcer and supported malignant melanoma. Although the lesion was rare, amelanotic, fragmented and associated with fibrosis, the defendant’s expert applied too lax a standard. His opinion treated the error as excusable rather than asking whether it fell below the objective standard fixed by law. The reasoning was therefore not defensible within the Bolitho exception, and breach was established.

4. Causation. On the balance of probabilities, the melanoma had metastasised to a detectable extent by November 2011. The claimant would have undergone wide excision in early January 2012. He would probably have declined a sentinel lymph node biopsy at that stage, because the relevant medical opinion was divided and he would have received balanced information under the NICE guidelines. The later diagnosis nevertheless meant that he would eventually have required lymph node procedures and substantially similar treatment.

5. The claimant recovered damages for the unnecessary narrow excision, associated pain and suffering, mental anguish and additional expense. The court awarded £12,000 for pain, suffering and loss of amenity, £500 for additional expenses and £4,000 for loss of earnings, making a total award of £16,500. The approach to loss of earnings was a broad estimate of the kind recognised in Blamire v South Cumbria Health Authority.

First instance decision. No prior appellate decision is stated in the judgment.