Skin Metastasis: Rare First Manifestation of Lung Cancer

A 74-year-old male patient complained of a rapidly growing mass on his back to the clinic, which grew from a bean large to approximately 3 cm in diameter within 3 months ([Fig. 1]). Upon physical examination, the mass was found round, hard, and protruding from the skin, with ulcers and black scabs visible on the surface, and a fixed boundary with the surrounding tissues. The patient presented a chronic cough as well without expectoration, hemoptysis, chest pain, or weight loss. He had a history of smoking and chronic obstructive pulmonary disease (COPD). As a routine examination before surgery, his chest computed tomography scan revealed a mass in the hilar of the left lung ([Fig. 2]). The patient was suggested for PET-CT (positron emission tomography-CT) examination, showing a malignant mass of increased metabolism (3.3 × 2.5 × 5.6 cm; SUVmax: 13.7) near the root of the left lung with a suspected lymph node metastasis in the mediastinum. There was also an abnormally increased metabolism in the subcutaneous soft tissue of the lower back (SUVmax: 6.6). The patient then underwent a bronchoscopic biopsy and was confirmed squamous cell carcinoma (SCC). He also underwent head-enhanced magnetic resonance imaging and bone scan with negative results. The resection of the lesion on the back was performed, and the histopathological analysis revealed metastatic SCC with the immunohistochemical analysis positive for P40 and P63 and negative for TTF-1 ([Fig. 3]). This patient is undergoing radiotherapy (60 Gy) and chemotherapy (Carboplatin 350 mg intravenous [i.v.], Paclitaxel 270 mg i.v., Creda 100 mg i.v.).

Fig. 1 A 3-cm in diameter round mass was found on the back of this patient.

Fig. 2 The chest computed tomography scan revealed a mass in the hilar of the left lung.

Fig. 3 The histopathological analysis revealed metastatic SCC (HE staing, 100X).

As the most frequently diagnosed nonskin cancer, lung cancer is often insidious with a continuous cough, hemoptysis, and weight loss as the main clinical manifestations. To date, lung cancer has been the leading cause of cancer-related death in male and female patients. Skin metastases as the first manifestation of lung cancer are rare. The possibility of the malignant tumor in this patient was easily covered by his long history of COPD and mere manifestation of a chronic cough. Skin metastases tend to be induced by aggressive, poorly differentiated cancers such as lung cancer and breast cancer. The most common sites of skin metastases are the anterior chest and abdomen. Skin metastases on the back are not common. A retrospective study showed that large cell lung cancer was the most likely type of lung cancer to metastasize to the skin, whereas SCC was the least likely. In fact, the possibility of simultaneous occurrence of skin SCC and lung SCC cannot be ruled out without a genetic test. The skin lesion could be a second malignancy that exists in one case.

In conclusion, physicians should not exclude the possibility of metastatic tumors for patients who complain of the lesion with a rapid enlargement. A detailed history and physical examination are necessary for a timely and accurate diagnosis of the primary disease. The adoption of genetic testing can help determine the origin of the disease.

Publication History

Article published online:
21 October 2022