Neuroblastoma: Viva

This is a branching oral built to probe the reasoning that holds the risk stratification and the paraneoplastic syndrome at the centre, and to expose the candidate who has memorised the headline without the safety-critical corners. The questions escalate from the framing to the staging, the molecular markers, the treatment pathway and the paraneoplastic syndrome, with deliberate probes into the spontaneous regression and the late effects. [1]

Opening question: framing the problem

The examiner opens with the mass and the periorbital ecchymosis and asks: how do you frame this problem in a single sentence, and what is your first step? [1]

A strong answer names the neuroblastoma from the abdominal mass crossing the midline, the catecholamine secretion and the periorbital ecchymosis of the orbital metastasis, and states that the first step is the confirmation of the catecholamine secretion and the staging of the disease extent. [1]

Model answer. This child has a metastatic neuroblastoma from the abdominal mass crossing the midline, the catecholamine secretion and the periorbital ecchymosis. The first step is to confirm the diagnosis with the urinary vanillylmandelic acid and homovanillic acid, to stage the disease with the iodine-123 metaiodobenzylguanidine scan and the magnetic resonance imaging, and to risk-stratify with the biopsy and the MYCN amplification status. [1][2]

Probe one: the staging system

The examiner presses: describe the International Neuroblastoma Risk Group staging system, and tell me what the image-defined risk factors are. [2]

A strong answer names the four stages and the meaning of the image-defined risk factors. The L1 stage is the localised tumour without the image-defined risk factors, the L2 stage is the locoregional tumour with one or more image-defined risk factors, the M stage is the distant metastatic disease, and the MS stage is the metastatic disease confined to the skin, the liver and the marrow in the infant under eighteen months. The image-defined risk factors include the extension across the midline, the encasement of the major vessels or nerves, the infiltration of the porta hepatis, the airway compression and the intraspinal extension. [2]

Pitfall probe. Why is the MS stage reserved for the infant under eighteen months, and what is its significance? Because the metastatic disease in the infant under eighteen months, confined to the skin, the liver and the marrow, carries the unique biology that may undergo the spontaneous regression, and the age cut-off of eighteen months is built into the staging system itself. [11][2]

Probe two: the MYCN amplification

The examiner asks: what is the MYCN amplification, and why does it matter? [5]

A strong answer names the MYCN amplification as the single most powerful adverse prognostic marker, present in roughly twenty percent of neuroblastomas, defined as more than ten copies of the gene per cell on chromosome two. The amplified MYCN drives the relentless proliferation and the treatment resistance, and its presence places the child in the high-risk group regardless of the stage or the age. [5][12]

Pitfall probe. Can a child with a localised tumour and the MYCN amplification be in the low-risk group? No, because the MYCN amplification overrides the stage and the age, and the amplified tumour is assigned to the high-risk group regardless of the localised presentation. [5][12]

Probe three: the high-risk treatment

The examiner asks: describe the treatment for the high-risk neuroblastoma, and tell me the survival. [1]

A strong answer names the five phases of the intensive multimodal therapy. The induction chemotherapy reduces the tumour, the surgical resection removes the primary, the myeloablative consolidation with the autologous stem cell rescue delivers the tumoricidal dose, the radiotherapy targets the primary site, and the anti-GD2 immunotherapy with the dinutuximab beta targets the minimal residual disease. The five-year survival remains below fifty percent despite the full sequence. [1][10]

Pitfall probe. What is the dinutuximab beta, and what is its toxicity? The dinutuximab beta is the monoclonal antibody that targets the GD2 disialoganglioside on the surface of the neuroblastoma cell, and its addition to the consolidation improved the event-free survival in the SIOPEN trial. The toxicity includes the neuropathic pain that demands the opioid analgesia, the capillary leak syndrome, the hypotension and the hypersensitivity. [10]

Branch one: the opsoclonus-myoclonus-ataxia syndrome

The examiner pivots: imagine instead a child who presents with the chaotic eye movements, the jerking limbs and the unsteady gait. What is this, and how does your approach change? [6]

A strong answer names the opsoclonus-myoclonus-ataxia syndrome as the paraneoplastic signature of the neuroblastoma, driven by the autoimmune response against the neural tissue that is cross-reactive with the tumour antigens. The opsoclonus is the chaotic multidirectional eye movement that is not the rhythmic nystagmus, and the child is neuroblastoma until proven otherwise. The search for the occult tumour, with the urinary catecholamines, the iodine-123 MIBG scan and the magnetic resonance imaging, is mandatory and urgent. The neuroblastoma associated with the syndrome is typically the low-stage, favourable-biology tumour, and the devastating fact is the poor neurological outcome despite the tumour cure. [6][9]

Pitfall probe. Why is the neurological outcome poor despite the tumour cure? Because the autoimmune cerebellar and brainstem injury persists, and the child may develop the cognitive, behavioural and motor sequelae that last for life. The early and aggressive immunomodulation with the corticosteroids, the intravenous immunoglobulin and the rituximab may improve the outcome. [9]

Branch two: the infant with stage MS

The examiner pivots again: return to the abdominal mass, but imagine a four-month-old infant with the skin nodules and the massive hepatomegaly. What is this, and how is it managed? [11]

A strong answer names the stage MS neuroblastoma, the metastatic disease confined to the skin, the liver and the marrow in the infant under eighteen months, which carries the unique biology of the potential spontaneous regression. The asymptomatic infant is managed with the observation and the supportive care, and the disease regresses without the treatment in the majority. The symptomatic infant with the respiratory compromise from the massive hepatomegaly receives the low-dose cyclophosphamide or the hepatic radiotherapy, and the five-year survival is above ninety percent. [11][1]

Closing question: counselling the family

The examiner closes: the diagnosis of the high-risk neuroblastoma is confirmed. How do you counsel the family? [1]

A strong answer describes the honest conversation that names the diagnosis, explains that the high-risk neuroblastoma carries a survival below fifty percent despite the most intensive treatment in the paediatric oncology, and that the treatment runs through the induction, the surgery, the myeloablative consolidation, the radiotherapy and the immunotherapy over approximately eighteen months. The family is introduced to the multidisciplinary team, given a written plan, taught the fever and the neutropenia emergencies, and supported by the social work and the educational liaison. The fellow who holds the science and the humanity together in this conversation demonstrates the reasoning the boards reward. [1][12]