A 2-year-old girl from Delhi presents with a 3-week history of irritability, poor feeding, and constipation. Her mother noticed a firm, non-tender mass in the left upper abdomen during bathing. On examination, blood pressure is 145/95 mmHg (elevated for age), and there is a fixed, hard mass palpable in the left flank. Serum creatinine is normal. Abdominal ultrasound reveals a 7 cm heterogeneous mass arising from the left adrenal gland with areas of calcification. 24-hour urine metanephrines are markedly elevated (8-fold normal). Which of the following is the most likely diagnosis?

Explanation

## Neuroblastoma: Clinical Presentation and Diagnosis ### Case Analysis This 2-year-old presents with the classic triad of neuroblastoma: 1. **Abdominal mass** (left adrenal origin) 2. **Systemic symptoms** (irritability, poor feeding, constipation) 3. **Hypertension** with elevated catecholamines (metanephrines) ### Neuroblastoma: Key Features **Key Point:** Neuroblastoma is a malignant tumor of neural crest origin arising from the sympathetic nervous system. It is the most common extracranial solid tumor in children and the most common tumor in infants. **High-Yield:** Neuroblastoma arises from: - Adrenal medulla (40% of cases) - Sympathetic chain ganglia (60% of cases) ### Clinical Presentation | Feature | Frequency | Details | |---------|-----------|----------| | Abdominal mass | 65% | Often discovered incidentally; firm, fixed, may cross midline | | Hypertension | 25–30% | Due to catecholamine secretion (epinephrine, norepinephrine) | | Systemic symptoms | 50% | Irritability, poor feeding, weight loss, fever | | Bone pain | 20% | From metastases to long bones | | Proptosis/periorbital ecchymosis | 5% | "Raccoon eyes" from orbital metastases | | Opsoclonus-myoclonus | 2–3% | Paraneoplastic syndrome | ### Biochemical Markers **Mnemonic for Neuroblastoma Markers:** **VMA-HVA** = Vanillylmandelic acid, Homovanillic acid (both elevated in urine). Also: **Catecholamines** (epinephrine, norepinephrine) and **Metanephrines** (metabolites) are elevated. **Key Point:** In this case, **24-hour urine metanephrines are 8-fold elevated**, which is pathognomonic for catecholamine-secreting tumors. Neuroblastoma secretes catecholamines in ~90% of cases, even if clinically silent. ### Imaging Findings - **Ultrasound:** Heterogeneous mass, often with calcification (stippled or coarse) - **CT/MRI:** Mass of adrenal or paravertebral origin; assess for local invasion and metastases - **MIBG scan:** Highly specific for neuroblastoma (uptake of metaiodobenzylguanidine) - **Bone scan or skeletal survey:** Assess for bone metastases ### INSS Staging (International Neuroblastoma Staging System) ```mermaid flowchart TD A[Neuroblastoma]:::outcome --> B{Tumor extent?}:::decision B -->|Localized, no crossing midline| C[Stage 1]:::outcome B -->|Localized, crosses midline| D[Stage 2A/2B]:::outcome B -->|Unilateral with nodes or bilateral| E[Stage 3]:::outcome B -->|Distant metastases| F[Stage 4]:::outcome B -->|Localized with MYCN amplification| G[Stage 4S]:::outcome C --> H[5-year survival: >95%]:::outcome D --> I[5-year survival: 90-95%]:::outcome E --> J[5-year survival: 70-80%]:::outcome F --> K[5-year survival: 40-50%]:::outcome G --> L[5-year survival: 90%]:::outcome ``` ### Risk Stratification **High-Yield:** Prognostic factors in neuroblastoma: - **MYCN amplification** (>10 copies): Poor prognosis; indicates high-risk disease - **Age at diagnosis:** <18 months = better prognosis - **Stage:** Stage 4S (special stage in infants <18 months with metastases to liver, skin, bone marrow) has excellent prognosis despite metastases - **Histology:** Favorable vs. unfavorable (Shimada classification) - **Ploidy:** Hyperdiploid tumors have better prognosis ### Why NOT the Other Options **Pheochromocytoma:** While pheochromocytomas do secrete catecholamines and cause hypertension, they are extremely rare in young children (typically adults >40 years) and arise from the adrenal medulla in a different context. The adrenal origin and age make neuroblastoma far more likely. **Wilms Tumor:** Wilms tumor arises from the kidney itself, not the adrenal gland. It does not typically cause hypertension or markedly elevated catecholamines. The imaging shows an adrenal mass, not a renal mass. **Adrenocortical Carcinoma:** While this can arise from the adrenal gland, it typically presents with virilization (in girls) or Cushing syndrome, not hypertension from catecholamine excess. Elevated metanephrines are not a feature of ACC. ### Management Approach 1. **Confirm diagnosis:** MIBG scan (highly specific), biopsy if needed 2. **Risk stratification:** MYCN status, age, stage, histology 3. **Treatment:** Surgery ± chemotherapy ± radiotherapy depending on risk group 4. **Monitoring:** Serial imaging, tumor markers (VMA, HVA, NSE) **Clinical Pearl:** Neuroblastoma has a unique feature: **spontaneous regression** can occur, especially in stage 4S infants. Some low-risk tumors may be observed rather than treated immediately. [cite:Park 26e Ch 13, Pediatric Oncology; Harrison 21e Ch 397]