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Title

HYPERTROPHIC OSTEOARTHROPATHY SECONDARY TO LUNG CANCER

Background

Hypertrophic osteoarthropathy (HOA) is a syndrome in which the main manifestation is digital clubbing associated with arthritis and periostitis in tubular bones. Systemic diseases may be associated with HOA, including lung cancer, cystic fibrosis, liver cirrhosis and Graves' disease.

Case report

CLSB, male, 52 years old. Presented to the rheumatology outpatient clinic with complaint of bilateral leg pain for 2 years. History of systemic arterial hypertension and smoking (35 packs-years). He reported muscle weakness in the lower limbs 15 days ago, needing crutches to walk. He denied low back pain, sphincter disorders or saddle anesthesia. There was fever, anorexia, and weight loss of 6 kg in 10 days. Alleged diagnosis of rheumatoid arthritis, in use of methotrexate and prednisone. Due to therapeutic failure, he stopped the treatment. The physical examination evidenced digital clubbing, bilateral quadriceps atrophy, muscle strength grading of the lower extremity: 3. Negative Babinski sign, and tibial pain associated to digitopression. Interned for diagnostic investigation. Laboratory tests revealed normocytic and normochromic anemia, erythrocyte sedimentation rate of 140 mm in the 1st hour, transaminases, creatine phosphokinase and aldolase were normal, rheumatoid factor, anti-nuclear antibody, p-ANCA and c-ANCA were negative. Double leg radiograph showed bilateral medial tibial and fibular periosteal thickening, with joint spaces preservation. Magnetic resonance imaging of the dorsal and lumbar spine evidenced foraminal disc protrusion in L2-L3, reducing the neural foramen amplitude. Digital clubbing and radiographic evidence of long bones periostitis confirmed the HOA hypothesis. Chest tomography showed a lung mass with irregular borders in the apical segment of the right lower lobe, measuring 7.4 x 6.0 x 5.7 cm without pleural cleavage plane and small left pleural effusion. The biopsy of the lung lesion was compatible with invasive adenocarcinoma. The pain was controlled with anti-inflammatory drugs. After initiation of cancer chemotherapy, the pain was resolved and the patient was able to walk spontaneously without crutches.

Conclusion

Lung cancer accounts for 80% of paraneoplastic HOA cases. Squamous cell carcinoma and adenocarcinoma are the most common histological types. Tibial pain is a typical symptom, but other long bones may be affected. Arthralgia in adjacent joints such as knees and ankles is common, and joint effusion may occur. Periostitis and bone pain usually respond to anti-inflammatory drugs. Zoledronic acid or pamidronate can be used in refractory cases. The rheumatologist should be alert to recognize the musculoskeletal syndromes associated with malignancies, making the treatment of the underlying neoplasm possible.

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