Childhood cancer warning signs and diagnostic pathways: Viva

This is a branching oral built to probe the reasoning that holds the persistent-progressive principle at the centre, and to expose the candidate who has memorised the tumour list without the discipline of the duration threshold. The questions escalate from the framing to the red flags, the front-line management, and the prevention of the delay, with deliberate probes into the leucocoria, the abdominal mass, and the cancer predisposition syndrome. [1]

Opening question: framing the problem

The examiner opens with the limp and the mass and asks how you frame this problem in a single sentence, and what the first question is that you ask of the history. [1]

A strong answer names the bone or the soft-tissue tumour cluster, and states that the first question is whether the symptom has crossed the line from a self-limiting into a persistent or a progressive course. The growing pains are bilateral, evening and free of daytime findings, and a unilateral, progressive, night pain that wakes the child, with a firm mass, is never a growing pain. [1]

Model answer. This boy has six weeks of unilateral, progressive, night-time leg pain with a firm thigh mass, which is a bone or a soft-tissue sarcoma until proven otherwise. My first question is whether the course is persistent and progressive, because the growing pains that this was attributed to are bilateral and free of daytime findings, and this presentation is not. [1]

Probe one: the five red-flag clusters

The examiner asks you to name the red-flag clusters that every paediatrician must hold, and to give the bedside finding that converts each into action. [1]

A strong answer names the five clusters. The leukaemia cluster is the pale, bruising, febrile child with the circulating blasts. The central nervous system cluster is the progressive headache with the early-morning vomiting and the papilloedema or the ataxia. The abdominal mass is the firm mass at bathtime. The lymphadenopathy cluster is the hard, fixed, painless node over two centimetres beyond four weeks. The eye cluster is the leucocoria on the red-reflex test. The bone and soft-tissue cluster is the progressive night pain with a mass. [1]

Pitfall probe. Which single bedside test converts the parental observation of a white eye on the flash photograph into a diagnosis? The red-reflex test, performed at around thirty centimetres in a dimmed room, which shows the white pupillary reflex of retinoblastoma and earns the urgent ophthalmology referral. [4]

Probe two: the front-line management

The examiner presses for exactly what you do at the front line, and what you deliberately do not do. [9]

A strong answer states that the front-line role is the recognition, the targeted triage tests, and the urgent referral, not the tissue diagnosis. The primary-care tests are the full blood count and film, the lactate dehydrogenase and the urate for a suspected malignancy, the plain radiograph then the magnetic resonance imaging for the bone tumour, and the ultrasound for the abdominal mass. The clinician must not delay the referral to perform the staging or the biopsy, which the treating centre repeats. The oncologic emergencies, the febrile neutropenia, the tumour lysis, the hyperleukocytosis and the mediastinal mass, are resuscitated first. [9]

Pitfall probe. Why must you not sedate the child with the mediastinal mass for a biopsy? Because the loss of the negative intrathoracic pressure on induction can collapse the airway that the mass is already compressing, and the airway must be secured before any sedation. [9]

Branch one: the leucocoria of retinoblastoma

The examiner pivots to an eighteen-month-old whose family reports a white glow in the eye on a flash photograph, and asks what this is and what you do. [4]

A strong answer names the leucocoria of retinoblastoma, the most common intraocular malignancy of childhood, with the median age under two years for the bilateral disease. The red-reflex test shows the white pupillary reflex, and the child is referred urgently to ophthalmology within days, because the early disease is curable and the late presentation with a painful red eye or a proptosis carries the worst prognosis. The hereditary retinoblastoma with the RB1 variant predisposes to the bilateral disease and to the later osteosarcoma, and earns the genetic testing and the lifelong surveillance. [4]

Branch two: the abdominal mass

The examiner pivots to a two-year-old with a firm mass found at bathtime, and asks how you separate a Wilms tumour from a neuroblastoma at the bedside and in the investigation. [8]

A strong answer states that the Wilms tumour is a smooth, firm, flank mass that does not cross the midline in a one-to-five-year-old, while the neuroblastoma is a hard, irregular mass that frequently crosses the midline and may carry the raccoon-eye ecchymoses, the hypertension and the opsoclonus. The ultrasound is the first imaging, and the urinary catecholamines, the vanillylmandelic acid and the homovanillic acid, separate the neuroblastoma from the Wilms tumour. Both are referred urgently to the paediatric oncology centre for the staging and the biopsy. [8]

Branch three: the cancer predisposition syndrome

The examiner pivots to a child whose father had a sarcoma at twenty and an aunt with early breast cancer, and asks how the family history changes your threshold. [10]

A strong answer names the Li-Fraumeni syndrome with the germline pathogenic variant in the TP53 gene, which predisposes to the soft-tissue and the bone sarcomas, the adrenocortical carcinoma, the brain tumours and the early-onset breast cancer. The family history lowers the threshold to investigate any persistent symptom, and the confirmed syndrome earns the scheduled whole-body and the brain surveillance into the adult life. The candidate names the other predisposition syndromes, the Down syndrome with the leukaemia risk, the Beckwith-Wiedemann with the Wilms tumour, and the hereditary retinoblastoma, and the principle that a known syndrome converts a low-probability symptom into a high-probability one. [10]

Closing question: preventing the delay

The examiner closes by asking how you would have prevented this boy's six-week delay, and the single principle you would teach a colleague. [1]

A strong answer states that the delay arose from the premature reassurance onto the growing pains, and that the prevention rests on the persistent-progressive principle and the safety-netting. The clinician who asks of every presentation whether it has crossed the line from a self-limiting into a persistent or a progressive course, who investigates the symptom that does not resolve, and who schedules the explicit review of the child sent home, is the clinician who catches the cancer early. The single principle is that the duration is the discriminator, not the single feature, and the scheduled review closes the loop. [1]