Multiple nodular lung metastases with no obvious primary showing low positive 18-fluoro deoxyglucose (FDG) uptake on positron emission tomography (PET) scan: A unique case of metastatic ameloblastoma

Introduction

The incidental detection of multiple secondaries in the lung, in an asymptomatic individual calls for detailed evaluation, especially if the 18-fluoro-deoxyglucose positron emission tomography (FDG PET) scan results are inconclusive or unusual.

Presentation of case

A 45 year old lady, asymptomatic, presented to us for evaluation of incidentally diagnosed, bilateral pulmonary metastases with a provisional diagnoses of advanced lung cancer. FDG PET scanning was inconclusive and revealed low positive FDG uptake. The biopsy revealed it to be metastatic ameloblastoma. She refused surgery but took only one cycle of chemotherapy with paclitaxel and carboplatin, which she then subsequently discontinued but continues to be asymptomatic at last followup.

Discussion

She gave history of previous ameloblastoma of the left mandible 13 years back, and recurrences 3 and 6 years later, which had been resected. For the last seven years she had no evidence of disease. History of past illness including operative interventions done for apparently benign or locally aggressive lesions of the oral cavity such as an ameloblastoma is important in evaluation of such cases.

Conclusion

Pulmonary metastases arising from an ameloblastoma maybe associated with low FDG positive uptake, and even though they are rare, it is important to diagnose them, since the prognosis and management of lesions from lung or other primaries and those from ameloblastoma are markedly different.