Rare cancers of head and neck

The area of head and neck is a relatively common primary location of childhood cancers (principally lymphomas, rhabdomyosarcomas, neuroblastoma, and germ-cell tumours). Malignant neoplasms of oropharynx, oral cavity, salivary glands or larynx, however, are very rare. Only about 0.6% of all oropharyngeal cancers are diagnosed in patients under the age of 20.

Nasopharyngeal carcinoma (NPC)

Nasopharyngeal carcinoma (NPC) is a very rare tumour in children aged 10–14 (incidence rate of 0.8 per 1 million) and in adolescents under the age of 19 (incidence rate of 1.3 per 1 million). It is virtually non-existent in children under the age of 10. NPC is typically diagnosed in endemic regions (Brazil). Infection with Epstein-Barr virus (EBV) is considered to be a risk factor for the development of NPC. Its clinical symptoms include nasal discharge and bleeding, nasal obstruction, often cervical lymphadenopathy; disorders of cranial nerves might also be present if the cranial base is affected. NPC is classified into three histological subtypes; types 2 and 3 occur most frequently in children (squamous and undifferentiated). Multimodal treatment is necessary (surgery, chemoradiotherapy). The five-year survival is about 80%.

NUT midline carcinoma

NUT midline carcinoma (NMC) is an extremely rare cancer that arises in the midline of the body, and is characterised by a chromosomal rearrangement in the nuclear protein in testis (NUT) gene. In approximately 75% of cases, the coding sequence of NUT on chromosome 15q14 is fused to BRD4 or BRD3, which creates a chimeric gene that encodes the BRD-NUT fusion protein. NMC is localised in the midline, often in the nasopharyngeal, oropharyngeal or mediastinal region. Clinical symptoms include upper airway obstruction, snoring, and bleeding from the oral cavity. NMC is a very aggressive tumour characterised by a rapid invasive growth into surrounding tissues; its prognosis is very poor. Radical resection is the only chance of cure, but the tumour often progresses locally even at early stages, and also produces distant metastases. Optimal treatment strategy is unknown due to a rare occurrence, and the prognosis is poor. Survival rates cannot be predicted due to the extremely rare occurrence.

Aesthesioneuroblastoma (olfactory neuroblastoma)

Aesthesioneuroblastoma (olfactory neuroblastoma) is an extremely rare cancer arising from the olfactory epithelium. Is is slightly more prevalent in boys, and typically occurs at the ages of 10–19. Its symptoms do not differ significantly from NPC symptoms (nasal obstruction, epistaxis, smell disorders). It can progress locally into surrounding tissues and organs (orbits, sinuses, frontal lobe of cerebrum). Its aetiology is unknown. Multimodal treatment is necessary (surgery, radiation and chemotherapy). Prognosis of the disease improved after the introduction of systemic chemotherapy: nowadays, more than 70% of patients are alive 5 years after diagnosis.

Thyroid cancer

Thyroid cancers account for about 1.5% of all paediatric cancers, and are significantly more common in adolescent girls. Preceding radiotherapy or hereditary cancer predisposition syndromes (MEN syndrome, Carney complex) play a role in the aetiology of thyroid cancers. Clinical symptoms involve a thyroid nodule (approximately 20% of them are malignant in children), or cervical lymphadenopathy. Thyroid cancers are classified according to their histology, aetiology and treatment strategies:

  1. Papillary thyroid cancer (60–75%) is usually multicentric, and spreads early to lymph nodes. It typically occurs at a pre-pubescent age, has an indolent course and a very good prognosis: more than 95% of patients are alive 5 years after diagnosis.
  2. Follicular thyroid cancer (10–20 %) can be sporadic or familial, and develops as an encapsulated solitary nodule. It typically occurs in adolescent age. It can spread to bones and lungs, but the prognosis is very good: the five-year survival is higher than 90%.
  3. Medullary thyroid cancer (5–10 %) is usually found in families with the MEN 2 syndrome. It has an aggressive course, and is usually treated surgically; biological therapy (vandetanib, cabozantinib) might be indicated for patients with unresectable carcinomas.
  4. Anaplastic thyroid cancer (less than 1%) has an aggressive course and a poor prognosis despite comprehensive treatment efforts.

Treatment of thyroid cancers is based on a radical resection (total thyroidectomy) followed by a radioactive iodine ablation therapy. Biological therapy (tyrosin kinase inhibitors – sorafenib) might be indicated for patients with recurrent papillary carcinoma.

Salivary gland cancer

Salivary gland cancers account for less than 5% of all head and neck cancers. Most of them are benign, only about 25% of them are malignant. They are more prevalent in adolescent girls, and arise from the parotid gland in most cases. Mucoepidermoid carcinomas prevail from the histological point of view, and usually have a low level of malignancy. Radical resection is the choice of treatment. Prognosis is usually good: more than 95% of patients are alive 5 years after diagnosis.

Pleomorphic adenoma prevails among benign tumours. Sialoblastoma is most common in the perinatal period. Sialoblastoma is a potentially aggressive epithelial tumour characterised by an invasive growth, and the possibility of local recurrence and regional metastases. From the histopathological point of view, it reflects various stages of development of the salivary gland. Its main clinical symptom is the rapid growth of a nodule, mainly in the parotid gland. Radical resection is the choice of treatment.