Metastatic tumors to the Jaws

Etiology and Pathophysiology

Contributory factors :

Originate from primary cancers elsewhere in the body:

• Breast

• lung

• prostate

• kidney

• thyroid

• Spread to bone is almost always from a carcinoma, usually an adenocarcinoma, and is haematogenous (blood-borne), often via Batson’s venous plexus

• Bronchus is also a recognised primary site

Prevalence

• Rare

• morelikely in cases of older adults (60+) and comprimised immune systems

• Accounts or 1% of oral malignancies

• Metastatic disease is the most common form of cancer involving the skeletal system, and jaw metastases are more common than primary malignant neoplasms of bone

• Metastasis to bone preferentially affects bones with the greatest medullary (marrow) volume — spine, pelvis, ribs, skull and femur — so jaw involvement is relatively unusual and usually signifies late-stage, widely disseminated disease

• In ~50% of cases the jaw metastasis is the first clinical evidence of an underlying malignancy (Cawson notes this is comparatively rare, more often a sign of already-known disease)

• Patients are usually middle-aged or elderly, reflecting the age distribution of the primary carcinomas

Histological Features

• Variable histology depending on the primary tumor

• Generally metastatic tumors exhibit

  • nuclear pleomoprhism
  • abundant mitotic figures
  • tissue invasion
  • well differentiated lesions may show keratin pearls

• Classically: infiltrating nests and cords of pleomorphic epithelial cells supported by a fibrous stroma

• The malignant tissue infiltrates adjacent marrow spaces and induces osteoclastic bone resorption

• Adenocarcinoma deposits may form glands and duct-like spaces within the medullary spaces

• Metastases are often poorly differentiated, so it may be difficult for the pathologist to determine the precise site of origin

• Histological appearances reproduce those of the primary carcinoma

Clinical Features

Location

• most commonly in the lower molar area

• The mandible is the most frequent site (~80% of cases), far more often than the maxilla; lesions favour the posterior mandible

• Deposits seed in the marrow spaces, and in the mandible most marrow lies below the inferior dental canal — this localisation helps distinguish metastases from tooth-associated lesions

Appearance

• Swelling: painless or painful enlargement of hte jaw

• Paraesthesia : Numbness or tingling due to nerve ocmpression

• Teeth mobility: lossening or displacement of teeth

• Pathological fractures

• Pain or swelling of the jaw, trismus, and paraesthesia/anaesthesia of the lip and chin

• Paraesthesia of the lower lip/chin is a major red flag for malignancy

• A non-healing tooth socket (or tumour proliferating from a recent extraction socket) is an important presentation for dentists

• Non-specific mucosal ulceration may occur in advanced cases with cortical bone destruction

• Many bony deposits are initially asymptomatic

Radiologically:

• Lesion has diffused borders

• The lesion erodes the cortical border (i.e. loss of cortical integrity)

• Osteolytic lesions: ill-defined, destructive radiolucency, often with a “moth-eaten” appearance; may have a hazy outline simulating an infected cyst or osteomyelitis

• Osteoblastic lesions: radiopaque or mixed radiolucent–radiopaque lesion due to reactive new-bone formation

  • Prostate carcinoma classically produces osteoblastic (sclerotic/opaque) deposits

• Small lesions can destroy the lamina dura around a root apex and be mistaken for a periapical granuloma, but have ragged margins

• May simulate periapical or periodontal disease — a diagnostic pitfall

Differential Diagnoses

• Primary jaw malignancy like osteo sarcoma of SCC
• Inflammatory/ necrotic
  • Osteoradionecrosis
  • MRONJ
  • Osteomyelitis
• Periapical granuloma / periapical (periodontal) disease (small osteolytic deposits may mimic these)
• Infected odontogenic cyst (hazy radiolucent outline can simulate this)
• Lymphoma (diffuse “moth-eaten” replacement of the entire mandibular medulla is typical of lymphoma)

Relevant Clinical Investigations

• Imaging

  • CBCT/OPG to assess bone destruction and tumor extent
  • CT/MRI to evaluate soft tissue involvement and metastasis spread

• Biopsy

• PET-CT for systemic metastais

• Full blood count , PSA for prostate cancer

• Biopsy is required for diagnosis in any new lesion; where extensive bony metastases are already known a biopsy is only confirmatory and will not alter treatment

• Submit all tissue removed during routine surgical procedures (including extraction sockets and apicectomy specimens) for histopathology — this is how occult metastases are detected

• PET scan can be used as an additional aid to detect metastatic lesions

Patient Management

• Multidisciplinary approach to collaborate with oncologists, surgeons and radiologists

• Palliative care to focus on pain relief and QoL

• Radiation therapy: targeted tx for local control

• Surgical resection

• Radiation and chemo

• Surgery and radiation and chemo

• Any suspicious soft-tissue or bony lesion should be biopsied

• Bone metastasis classifies the patient as stage IV disease, with corresponding prognostic implications; the treatment modality chosen depends on the primary tumour itself

• Prognosis is poor — jaw involvement usually signifies widely disseminated disease, with survival typically less than one year after diagnosis

Case Study: Prostate Metastasis

A patient presented with a dense, radiopaque (osteoblastic) area in the mandible and ulceration of the mucosa. The lesion was a metastatic deposit from a primary prostate carcinoma, illustrating how metastatic disease can mimic primary bone tumours or periodontal disease.