Dr. Pepe’s Diploma Casebook: CASE 123 – SOLVED!

Findings: Lateral view of the ankle shows an ill-defined anterior cortical lytic lesion (A, arrow), seen as a hypodense area in the AP view (B, circle). Bone scan confirms a single bone lesion (C, arrow).

MR images show an anterior cortical mass (D and E, arrows), suspected to be a bone sarcoma. Tru-cut biopsy findings diagnosed metastatic adenocarcinoma. The chest radiograph showed a left paramediastinal pulmonary mass (F, arrow). Biopsy confirmed adenocarcinoma of the lung.

Final diagnosis: tibial cortical metastasis from lung carcinoma

Most of us are familiar with the common manifestations of lung carcinoma in the chest radiograph. Today I would like to address an unusual form of presentation: extrapulmonary metastasis as the first manifestation of the disease. This presentation form occurs in about 1% of patients. It should be kept in mind to avoid misdiagnoses and treatment delays.
In this chapter I would like to review the most common sites of metastasis as the initial manifestation of a lung tumor.

About half the metastases from undiagnosed lung cancer occur in the skeleton. Remember that most bone malignancies in adults are metastatic lesions rather than primary bone tumors, with a ratio of about 20 to 1.

Pain is the most common symptom in skeletal metastasis. When it is the initial symptom of unknown lung cancer, in most cases (80%) the spine is the affected site (Fig. 1). The remaining 20% involve the femur, pelvis or humerus (Fig. 2). Metastasis to the distal extremities is highly suspect of a lung primary (Fig. 3).

Fig. 1. 89-year-old man with increasing back pain for the last 4 months. Radiographs on admission show a lytic lesion in the anterior aspect of L3 (B, circle), confirmed on sagittal CT (C, circle). 

The chest radiograph at this time shows a left parahilar mass (D, arrow). Enhanced axial CT confirms an irregular left lung mass. Diagnosis: carcinoma of the lung with metastasis to the lumbar spine.

Hypertrophic osteoarthropathy is a paraneoplastic syndrome associated with lung cancer, characterized by pain and extensive periostitis of the hands and long bones. Its discovery should prompt a chest radiograph to investigate a chest malignancy (Fig. 4).

The brain is a common target for lung metastasis, but it is rarely the first site of symptoms (Figs. 5 and 6). It has been reported that brain metastasis is the first manifestation of lung cancer in 2% of patients. The brain was the only metastatic site in 75% of these patients.

Coronal and sagittal CT confirm the presence of a large mass (C and D, arrows). Final diagnosis: lung carcinoma with metastasis to the brain.

Metastasis to the skeletal muscle occurs in less than 1.5% of lung cancers, usually in advanced phases of the disease. Occasionally, the metastatic lesions cause the first symptoms and should not be confused with a soft tissue sarcoma, which has similar clinical and radiologic features (Fig. 7).

PA chest radiograph taken after the biopsy shows a double contour of the aortic knob (D, arrow), secondary to a barely visible lung mass in the anterior clear space in the lateral view (E, arrow). Enhanced axial CT confirmed the mass (insert, arrow).
Diagnosis: adenocarcinoma

Extrathoracic metastatic lymph nodes can simulate soft tissue masses and may be interpreted initially as primary soft tissue tumors (Fig. 8).

Enhanced coronal CT shows a peripheral mass (C, white arrow) and hilar and mediastinal nodes (C, red arrows). Axial CT of the groin confirms an enlarged lymph node (D, arrow). Final diagnosis: adenocarcinoma of the lung with mediastinal metastases and a single metastatic lymph node in the left groin.

Pancreatic metastasis from lung carcinoma is not uncommon and usually found in advanced cases. Pancreatitis is an unusual form of initial presentation provoked by pancreatic metastasis, which is said to occur in less than 0.1% of patients (Fig. 8).

Follow Dr. Pepe’s advice:

1. About half of initially-appearing lung metastases occur in the skeleton.

2. Malignant-appearing bone lesions in the hands or feet should prompt a CXR.

3. Brain metastasis as the initial presentation occurs in about 2% of lung cancer cases.

4. Do not confuse muscle metastasis with soft tissue sarcoma.