This article describes a rare occurrence of lung cancer metastasizing to the anus.
The patient presented to the hospital with fatigue, weight loss, and loss of appetite. On history, he revealed he was a heavy smoker. Doctors found an opacity in the apical region of his left lung on X-ray. The opacity consistent with findings such as weight loss and loss of appetite aroused suspicion for lung cancer. To confirm it, doctors ordered a CT scan which showed calcifications in the apical lung field along with positive mediastinal lymph nodes as well.
Histopathology for Lung Cancer and Mets
The histopathological analysis revealed non-small cell lung cancer of the adenocarcinoma type. Moreover, doctors performed a CT abdomen and pelvis to look for any Mets. They did not find any. However, on a PET scan, they noticed that the Pancoast tumor was invading the thoracic vertebrae. In addition, the tumor also infiltrated the brachial plexus. Doctors treated the patient with radiotherapy until his symptoms started improving.
Subsequent Presentations of the Patient
The patient presented again after a while with complaints of tenderness in the left lower chest wall. CT indicated the involvement of the liver and adrenals. Doctors performed another PET scan to get a clearer picture. It revealed high uptake in bilateral adrenals as well as the anal area.
Doctors referred the patient for surgery on complaints of severe perianal pain and a mass near the anal orifice. Resection of the mass and subsequent histopathology revealed a metastatic lung tumor. He also received palliative care. However, the patient did not survive.
Lung Cancer and Its Subtypes
Lung cancer is one of the most common cancers causing deaths worldwide. Doctors classify this cancer into two broad categories; small cell lung cancer and non-small-cell lung cancer. Both have their own treatment plans and overall prognosis.
Among non-small lung cancers, adenocarcinomas occur most frequently followed by squamous cell carcinomas. Moreover, these metastasize using hematogenous and lymphatic routes to bone, brain, and adrenal glands.
Metastasis to Intestines
Lung cancers do not commonly metastasize to the gastrointestinal tract. However, via the lymphatic route, they can invade the esophagus through direct extension and the stomach and sometimes small intestines. Our case represents an incidence of lung cancer metastasis to the anus. There are only a handful of such cases and doctors still struggle to suggest a definitive route for this metastasis. Some suggest that cancer reaches the anus through lymphatics from the lung to the mediastinum to the intestines. Overall, people with a history of smoking and high-risk populations for lung cancer should undergo a thorough evaluation of any peri-anal fistulas or abscesses as these can be potential Mets from a lung tumor.
In all such cases after careful examination and investigation, a combination of chemotherapy and radiotherapy is indicated. Surgery is not usually preferred as it does not affect the outcomes other than relieving the anal symptoms if the patient is highly symptomatic. Doctors suggest palliative surgery only in cases where the patient has severe bleeding, an external mass, or anal obstruction. Nevertheless, survival in all such cases comes out to be extremely low.
Thus, perianal lesions in people with lung cancer should be carefully assessed. A surgical biopsy can also be performed for the purpose of establishing a diagnosis as most such cases easily go misdiagnosed and affect the overall prognosis.
