A 69-year-old man presents with a painful mass on the anterior aspect of his right knee. The mass has grown from a pimple-sized lesion to a mass the size of a golf ball over the last 3 weeks. The patient has a history of stage-4 lung cancer, coronary artery disease, and gastroesophageal reflux disease. The patient is being worked up for difficulty swallowing as an inpatient, and the attending hospitalist requested a consult for presumed prepatellar bursitis. The patient’s white blood cell count on admission was slightly elevated, but he remains afebrile. On examination, the patient has a purple golf-ball-sized subcutaneous mass just distal to the inferior pole of the patella. The mass is firm and very painful to touch. An aspiration is attempted, and a small amount (2 mL) of blood-tinged fluid is aspirated. A magnetic resonance imaging scan with contrast reveals a round, solid, subcutaneous mass of approximately 3 cm in size anterior to the tibia that shows contrast enhancement throughout.
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Cutaneous metastases or metastatic skin lesions from lung cancer are rare; skin lesions are only the 13th most common site of metastases from lung cancer. Cutaneous metastases are usually found close to the site of the primary tumor, but they may occur anywhere on the skin. Lymphatic and vascular routes are the most common pathways for cancers to spread.
Patients who present with skin metastases usually have multiple metastatic sites throughout the body. Mean survival is approximately 5 to 6 months.
Metastatic skin lesions do not have a characteristic presentation, as the color, shape, location, and symptoms can vary. Histologic presentation also varies, as cells from metastatic lung cancer may be poorly differentiated. The diagnosis is confirmed when histologic findings from the metastatic lesion and the primary site are similar.
When skin metastases occur, the cancer is often so widespread that the condition is untreatable, and palliative care may be recommended. Local treatments, including cryotherapy, chemotherapy, and surgical excision, are other options that can help improve the patient’s quality of life.
Dagan Cloutier, MPAS, PA-C, practices in a multispeciality orthopedic group in the southern New Hampshire region and is editor in chief of the Journal of Orthopedics for Physician Assistants (JOPA).
- Mollet TW, Garcia CA, Koester G. Skin metastases from lung cancer. Dermatol Online J. 2009;15(5):1.