Chronic shoulder pain with recent onset of fingernail clubbing can be an ominous sign, in this case heralding the presence of lung cancer. Lung tumors, especially Pancoast tumors, not infrequently mimic musculoskeletal conditions of the shoulder. Consider adding a chest film to the workup of shoulder pain in the proper clinical setting or when there are no positive findings on examination of the shoulder.
Table 1 lists the differential diagnostic considerations of shoulder pain. Table 2 offers some useful tips about fingernails.
It is uncertain whether this patient also had tendinitis: visceral conditions, including coronary artery disease can occasionally aggravate preexisting musculoskeletal conditions. Therefore, be wary of ending your diagnostic process prematurely when a second condition may be present. Chest films for this patient show a pulmonary mass at the right hilar area (Figure 2).
Table 1. Quick essentials on shoulder pain differential diagnosis
Anterior: Acromio-clavicular joint arthritis, glenohumeral joint arthritis, biceps tendinitis
Posterior: Neck conditions, suprascapular nerve entrapment
Lateral: Impingement, tendinitis, rotator cuff (all usually aggravated by reaching overhead)
Other: Brachial plexus, vascular disease, thoracic outlet syndrome, lung tumor, myocardial infarction, abdominal aortic aneurysm, pericarditis, GI disease
Table 2.Quick essentials on fingernail conditions
Fingernails: Made of keratin. Average growth rate: 3 mm/mo for fingers; 1 mm/mo for toes
White lines: Muehrcke lines: low albumin; Mees lines: arsenic; nail base lines: paraneoplastic disease
Fungus: Trichophyton rubrum infection in 90%. Risks: tight shoes, peripheral vascular disease, HIV infection, tobacco. Rx: terbinafine(Drug information on terbinafine) (≈ 45% relapse at 3 years)
Clubbing: "CLUB": Congenital, Cardiac, Cirrhosis, Lung disease, Ulcerative colitis, Biliary disease
Other: HIV infection, hyperthyroidism