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A 60-year-old man presents to an emergency department in Dammam, Saudi Arabia, with ongoing burning pain in his right shoulder. He notes that the pain began about 6 months earlier, has gradually worsened, and has not responded to pain killers. He says he experiences the pain throughout the day, and rates it as 7 out of 10 on the severity scale. He explains that the pain has started to interfere with his sleep and quality of life, that it is non-radiating, and that he has no weakness or sensory changes.

The patient notes that his work involves manual labor, but that he has not had an injury that might account for the pain. He says he has been assessed by several general practitioners and was diagnosed with rotator cuff injury based on the nature of his work. He was prescribed several analgesics as well as physiotherapy, but neither of these measures has relieved the pain.

The patient is in otherwise good health, with no history of chest pain, shortness of breath, cough, headache, or seizures. He notes no changes in appetite or weight, and his medical and surgical history are unremarkable. He notes that he quit smoking cigarettes about 2 years earlier, after a 30 pack-year history.

Physical Examination

Physical exam shows the following:

• Blood pressure: 110/70 mm Hg

• Heart rate: 90 beats/min

• Respiratory rate: 14 breaths/min

• Temperature: 37.0°C

• Oxygen saturation: 98% on room air

The patient is neither cachectic nor pale, and clinicians find no evidence of lymphadenopathy or clubbing. Examination of his shoulders shows no deformity or muscle atrophy, although his right arm has limited range of motion due to the pain. Cardiorespiratory and neurological examinations are normal.

X-ray assessment of the shoulder reveals apical opacity in the right lung, and based on a strong suspicion of malignancy, clinicians order an urgent thoracic CT scan. This reveals a necrotic mass of 10.5 × 10.5 × 8.0 cm in the right upper lobe, with chest wall and mediastinal invasion, resulting in destruction of the first and second posterior ribs.

Additional assessment with magnetic resonance imaging shows a lobulated heterogeneous mass invading the middle and inferior trunks of the right brachial plexus.

CT-guided biopsy and histopathological examination of the specimen reveals a poorly differentiated carcinoma. Another CT scan is performed for staging, which shows multiple lesions scattered within the cerebral and cerebellar hemispheres with associated edema. While the CT results suggest metastatic disease, the patient's bone scan shows no evidence of metastasis.

The advanced stage of the disease requires a palliative approach, so the clinicians arrange a time with the patient for a regional nerve block to manage his shoulder pain. He declines this option and asks to continue his oral analgesics, including paracetamol 1 g three times/day, tramadol 100 mg three times/day, and amitriptyline 10 mg/day.

Two weeks later, the patient begins to have frequent headaches and has to use a wheelchair due to gait instability. Clinicians note a change in his voice; his pupil size is notably smaller and his right eyelid begins to droop -- typical signs of . Palliative treatment was continued, with adjustments in the prescribed medications.

Discussion

Clinicians presenting this of a former smoker with what turned out to be metastatic lung cancer -- who presented solely with shoulder pain -- note that because some common symptoms may indicate serious underlying pathology, they require a high index of suspicion.

An estimated 20% of consultations in general practice are related to musculoskeletal conditions, which remain a leading cause of morbidity. Furthermore, shoulder pain is the third most common musculoskeletal complaint among patients seeking medical care. While etiology is typically orthopedic or rheumatological in nature, shoulder pain can also be a presenting sign of serious medical conditions, including myocardial infarction, hepatobiliary diseases, and lung cancer.

The case authors note that the patient's age and history of manual labor, along with the absence of any respiratory symptoms, led to the misdiagnosis of rotator cuff injury. Superior pulmonary sulcus tumor, or Pancoast tumor, is uncommon, accounting for 3%-5% of lung cancers.

The tumor's distinct anatomical location may result in local invasion of the brachial plexus and stellate ganglion, so that patients present with symptoms suggestive of a musculoskeletal disorder affecting the shoulder. This can lead to delayed diagnosis, as occurred in this case. Less than 2% of patients with Pancoast tumor have a normal chest x-ray, so a simple investigation can allow for timely diagnosis -- and appropriate -- given clinician awareness and a sufficient degree of suspicion.

Differential diagnosis of shoulder pain includes a wide range of gastrointestinal, neurological, cardiological, and rheumatological conditions. Thus, a careful history and physical examination are needed to reach the correct diagnosis.

Signs that this patient's symptoms were not due to a musculoskeletal problem are the unremitting nature of his pain and its interference with activities of daily living.

Lung cancer has a wide range of , which can result from intrathoracic effects of the tumor, extrathoracic spread, or paraneoplastic phenomena. Studies show that intrathoracic effects of lung cancer tend to cause symptoms such as cough (55% of patients), dyspnea (45%), and pain (38%), and up to 10% of cases of small-cell lung cancer involve superior vena cava syndrome.

Furthermore, lung cancer can spread and the presenting symptoms can be related to metastases to any part of the body. Paraneoplastic phenomena -- which include a variety of endocrine, neurological, hematological, and rheumatological syndromes -- are reported in up to 10% of lung cancers.

Conclusions

The case authors conclude that physicians should remain alert to the possibility of Pancoast tumors in patients who are heavy smokers, and that chest x-ray should be performed in older patients and smokers with shoulder pain.

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