Lung cancer is one of the most common cancers and a leading cause of cancer associated death.1 About 50% of all lung cancers have distant metastasis at the diagnosis.2,3 The gastrointestinal system is rarely involved.1,4 Symptomatic colonic metastasis is extremely rare, with an estimated incidence of 0.2–0.5%, and usually only clinically identified in advanced stages.1 Likewise, metastases to the oral cavity are very uncommon, however they can be the first manifestation of a primary tumor.5

An 82-year-old woman presented to the emergency department with a 15-day history of diarrhea (no blood or mucus), intermittent abdominal pain and asthenia. No fever associated and no history of cancer or smoking habits. Her medical history included hypertension, dyslipidemia, renal lithiasis and total hysterectomy. She had been followed up in stomatology in the previous month, for the recent appearance of an exophytic lesion in the lower right gingival. On emergency admission, physical examination revealed a palpable, bulky abdominal mass on the left flank and umbilical region. Blood tests revealed anemia (9.1g/dL), leukocytosis (20.55×109/L), neutrophilia (17.3×109/L) and high C reactive protein (27mg/dL). Thoracic and abdominal computed tomography scan showed two masses, one in the pulmonary right upper lobe, measuring 90mm×87mm, and the second on the left flank with 103mm×83mm (Fig. 1A and B). Abdominal, lung and gingival lesions histopathology revealed poorly differentiated pulmonary adenocarcinoma. Immunohistochemistry was negative for CDX2, cytokeratin20, GATA-3 and reactive for CK7 and TTF-1 (Fig. 1C–E). These findings support that the metastatic lesions were from a primary lung carcinoma. Unfortunately, the patient died two months after the diagnosis due to an infectious complication.

Fig. 1.

(A) Thoracic scan showing a pulmonary mass in the right upper lobe, measuring 90mm×87mm. (B) Abdominal and pelvic CT scan showing a mass on the left flank with 103mm×83mm. (C and D) The tumor cells express both TTF-1 and cytokeratin 7, which is compatible with pulmonary origin. (E) H&E staining: poorly differentiated adenocarcinoma.

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The case we report is an exceptionally rare presentation of synchronous colonic and gum metastasis of primary lung adenocarcinoma. The exact incidence of lung adenocarcinoma metastases to the colon is unknown because most of them are from squamous and large cell carcinomas.1 Metastasis in the oral mucosa are also very rare, with a poor prognosis. These metastasis may be the initial manifestation of neoplasia in about a quarter of cases, although they are frequently confused with benign lesions of the oral soft tissues.5

This report emphasizes that exophytic gingival lesions of recent appearance, despite patterns of benignity, should be actively examined and a biopsy should be carried out for definitive diagnosis.