47  Other Pediatric Tumours

47.1 Introduction

Childhood cancers represent a diverse group of diseases distinct from adult malignancies in their biology, clinical behaviour, and response to treatment. While leukaemias, lymphomas, nephroblastoma, and retinoblastoma are among the most common, several other solid tumours also contribute significantly to paediatric cancer morbidity and mortality worldwide.

Understanding these conditions is crucial for early recognition, appropriate referral, and timely management. This chapter will cover neuroblastoma, hepatic tumours, sarcomas, bone tumours, brain tumours, and germ cell tumours, as well as selected rare entities.

47.2 Neuroblastoma

47.2.1 Introduction and Epidemiology

Neuroblastoma is the most common extracranial solid tumour of childhood, arising from neural crest cells of the sympathetic nervous system.
- Accounts for about 8–10% of childhood cancers.
- Median age at diagnosis: 2 years.
- Rare after 10 years.
- Common sites: adrenal medulla (40%), paraspinal sympathetic chain, posterior mediastinum.

47.2.2 Pathophysiology

• Originates from neural crest cells that fail to differentiate.
  
• Tumour behaviour is highly variable: can spontaneously regress (especially in infants) or progress aggressively with widespread metastases.
  
• Genetic features: amplification of MYCN oncogene is associated with poor prognosis.

47.2.3 Clinical Features

• Abdominal mass (often firm, irregular, crossing midline).
  
• Symptoms due to local invasion: constipation, urinary obstruction.
  
• Metastases: bone pain, periorbital ecchymoses (“raccoon eyes”), hepatomegaly.
  
• Paraneoplastic features: hypertension, diarrhoea (due to vasoactive intestinal peptide).

47.2.4 Investigations

• Imaging: ultrasound, CT/MRI of abdomen.
  
• MIBG scan: identifies tumour sites.
  
• Biopsy for histology.
  
• Elevated urinary catecholamines (VMA, HVA) in >90%.

47.2.5 Management

• Depends on risk stratification.
  
• Low-risk: Surgery alone may cure.
  
• Intermediate-risk: surgery + chemotherapy.
  
• High-risk: intensive chemotherapy, surgery, radiotherapy, stem cell transplant, immunotherapy.

47.2.6 Prognosis

• Variable. Infants with localised disease may do very well.
  
• High-risk disease has poorer survival despite aggressive therapy.

47.3 Hepatic Tumours

47.3.1 Hepatoblastoma

• Most common primary liver tumour in children.
  
• Usually diagnosed in children under 3 years.
  
• Associated with prematurity and some genetic syndromes (e.g., Beckwith–Wiedemann).

Clinical Features:
- Painless abdominal mass.
- Abdominal distension.
- Elevated alpha-fetoprotein (AFP) in most cases.

Diagnosis:
- Ultrasound/CT scan showing liver mass.
- Biopsy for confirmation.

Treatment:
- Surgical resection (hepatectomy).
- Neoadjuvant/adjuvant chemotherapy (cisplatin-based).
- Liver transplant if unresectable.

Prognosis:
- Good if complete surgical removal is possible.

47.3.2 Hepatocellular Carcinoma (HCC)

• Less common in children but important in sub-Saharan Africa due to hepatitis B infection.
  
• Presents in older children and adolescents.
  
• AFP is elevated but less consistently than hepatoblastoma.
  
• Prognosis is generally poor, as tumours are often unresectable.

47.4 Rhabdomyosarcoma and Other Soft Tissue Sarcomas

47.4.1 Rhabdomyosarcoma (RMS)

• Most common soft tissue sarcoma in children.
  
• Arises from primitive mesenchymal cells committed to skeletal muscle lineage.
  
• Common sites: head and neck (orbit, nasopharynx), genitourinary tract, extremities.

Clinical Features:
- Mass on the affected site.
- Proptosis (orbital).
- Nasal obstruction, epistaxis (nasopharyngeal).
- Haematuria or vaginal bleeding (genitourinary).

Diagnosis:
- Imaging (MRI).
- Biopsy with histology (embryonal, alveolar, pleomorphic subtypes).
- Immunohistochemistry (desmin, myogenin positive).

Treatment:
- Multimodal: surgery, chemotherapy, radiotherapy.

Prognosis:
- Better in embryonal type.
- Depends on site, size, and extent.

47.4.2 Other Soft Tissue Sarcomas

• Include fibrosarcoma, synovial sarcoma, and malignant peripheral nerve sheath tumour.
  
• Less common but managed similarly with surgery, chemotherapy, and radiotherapy.

47.5 Bone Tumours

47.5.1 Osteosarcoma

• Most common primary malignant bone tumour in children and adolescents.
  
• Peak in adolescence during rapid bone growth.
  
• Common sites: metaphyses of long bones (femur, tibia, humerus).

Clinical Features:
- Localised bone pain (worse at night).
- Swelling, mass, limitation of movement.
- Pathological fractures may occur.

Investigations:
- X-ray: mixed lytic-sclerotic lesion, periosteal reaction (“sunburst” appearance, Codman triangle).
- MRI: local extent.
- Biopsy confirms diagnosis.

Treatment:
- Neoadjuvant chemotherapy, limb-sparing surgery (or amputation), adjuvant chemotherapy.

Prognosis:
- Improved with multimodal therapy.
- Presence of metastases (lung) worsens outlook.

47.5.2 Ewing Sarcoma

• Second most common bone tumour in children.
  
• Arises from primitive neuroectodermal cells.
  
• Typically affects diaphysis of long bones and pelvis.
  
• Associated with t(11;22) translocation.

Clinical Features:
- Pain, swelling, systemic symptoms (fever, weight loss).
- Can mimic infection (osteomyelitis).

Investigations:
- X-ray: “onion-skin” periosteal reaction.
- MRI: extent of disease.
- Biopsy for histology and cytogenetics.

Treatment:
- Chemotherapy, surgery, and/or radiotherapy.

Prognosis:
- Fair with localised disease.
- Poor with metastases.

47.6 Brain Tumours

Brain tumours are the most common solid tumours of childhood.

47.6.1 Medulloblastoma

• Most common malignant brain tumour in children.
  
• Originates in cerebellum.
  
• Highly radiosensitive.

Features: headache, vomiting, ataxia, papilloedema.
Treatment: surgery + craniospinal irradiation + chemotherapy.

47.6.2 Astrocytomas

• Low-grade astrocytomas (e.g., pilocytic astrocytoma) have excellent prognosis after surgical removal.
  
• High-grade astrocytomas are aggressive and carry poorer outcomes.

47.6.3 Ependymomas

• Arise from ependymal cells lining ventricles.
  
• Commonly present with hydrocephalus due to obstruction.
  
• Treatment: surgery and radiotherapy.

47.7 Germ Cell Tumours

47.7.1 Overview

• Can occur in gonads (testis, ovary) or extragonadal sites (sacrococcygeal, mediastinum, retroperitoneum).
  
• Derived from primordial germ cells.

47.7.2 Clinical Features

• Testicular: painless testicular mass.
  
• Ovarian: abdominal mass, pain, precocious puberty.
  
• Sacrococcygeal: mass at base of spine, sometimes visible externally.

47.7.3 Diagnosis

• Imaging (ultrasound, CT/MRI).
  
• Serum tumour markers: AFP, β-HCG.
  
• Biopsy (except in some gonadal cases where orchiectomy/oophorectomy is primary treatment).

47.7.4 Treatment

• Surgery + chemotherapy (cisplatin-based).
  
• Prognosis generally good, especially for localised disease.

47.8 Other Rare Paediatric Tumours

• Adrenocortical tumours: may present with virilisation or Cushing’s syndrome.
  
• Thyroid carcinoma: uncommon, but papillary carcinoma can occur, sometimes associated with prior radiation exposure.
  
• Malignant rhabdoid tumour of the kidney or brain: rare and aggressive.

47.9 Conclusion

Beyond leukaemia, lymphoma, nephroblastoma, and retinoblastoma, several other paediatric malignancies play a significant role in the spectrum of childhood cancer. These include neuroblastoma, hepatic tumours, sarcomas, bone tumours, brain tumours, and germ cell tumours. Although they differ in biology and clinical behaviour, successful management relies on early diagnosis, multidisciplinary care, and supportive management.

In resource-limited settings such as Ghana, improving survival will require increased awareness of early signs, timely referral, access to diagnostic facilities, and strengthening of paediatric oncology units.