A 7-year-old boy presented with swelling of metacarpals, metatarsals, and phalanges of his hands and feet. He had swelling associated with aching pain since he was one year of age. He was diagnosed with polyarthritis at that time. After one month of treatment, his symptoms were not changed, and he was transferred to VNC Hospital. He was diagnosed with Pediatric Skeletal Dysplasia (at that time, the patient had no signs of pleural and peritoneal effusion). There was no improvement after two months of treatment, and he was treated with traditional medicine. A few days before admission to HPC Hospital, all metacarpals, metatarsals, and phalanges of his hands and feet were swollen and painful. Moreover, he had poor appetite, fatigue, and abdominal distension. He was hospitalized in HPC Hospital. On physical examination, he was thin, and his body weight was 18kg. The pulse rate was 105/min, and the respiratory rate was 30/min. The body temperature was 37.0°C. The infection syndromes were unclear. The patient had anemia manifestations: pale skin and mucosa. Physical examination revealed the visibly enlarged distal interphalangeal (DIP) joint of the left middle finger, the proximal interphalangeal (PIP) joint of the right index finger, and the interphalangeal joint of the left great toe with a firm, fusiform swelling that involved the proximal and middle phalanges, with overlying erythema (See ). The knuckles of his hand and feet were sore and scaly spots on the skin surface. The patient had atrophy of the forearm muscles, arm muscles, thigh muscles, leg muscles on both sides. The joints were moved within normal limits. Tendon reflex was normal. In addition, the patient had spleno-hepatomegaly, collateral circulation, and ascites. A dull percussion sound was noted in the left lung. History of local trauma, cough, bowel disturbances, and immunosuppression was negative. A provisional diagnosis of polyarthritis was made, and the differential diagnosis was bone cancer. His complete blood count showed moderate anemia (erythrocyte count 3.71x1012/L, hemoglobin of 74g/L), white blood cells count 7.49 x109/L with 52.7% neutrophils, and platelets count 410 x109/L. His erythrocyte sedimentation rate (ESR) was 42 mm/hour, and C -reactive protein (CRP) was 24 mg/L. Liver function tests revealed normal bilirubin and transaminases. Serum electrolytes test showed Na+ 135 mmol/l; K+ 3.4mmol/l; Cl− 103mmol/l; total calcium 2.1 mmol/l; ionized calcium 0.89 mmol/l. The urinalysis test was normal. Abdominal ultrasound showed ascites, hepatomegaly, splenomegaly, and other organs were normal. X-rays of hands and feet showed decreased joint space with periarticular erosions and subluxation, suggesting that the patient might have tuberculous arthritis (See ). Chest ultrasound revealed left pleural effusion with 3cm-thick fluid along the middle axillary line, the fifth intercostal space, and revealed a little fluid in the pericardium. Chest X-ray showed pleural effusion (See ). QuantiFERON-TB test was positive. Rivalta test was positive, much higher in protein content (46g/l) On dermatology examination, there were some skin lesions with fibrinous bases and tuberculous gummas. Because of the clinical characteristics lasting for many years and the laboratory investigations, the patient was diagnosed with Spina Ventosa at a later stage. Eventually, he was transferred to NL Hospital. At the NL Hospital, laboratory investigations were as follows: Hands and feet X-rays showed decreased joint space with periarticular erosions and subluxation correlated with the signs of tuberculous arthritis. The chest CT scanner showed pleural effusion. QuantiFERON-TB test was positive (++). The histopathological examination revealed epithelioid granuloma, which indicates tuberculosis. Serum CRP increased to 126 mg/l. Liver and kidney function tests were normal. Abdominal ultrasound showed ascites, hepatomegaly, and splenomegaly. The child was diagnosed with Spina Ventosa and was treated with anti-tuberculosis drugs - RHZE (Rifampicin, Isoniazid, Ethambutol, and Pyrazinamide) for two months. His lesions recovered after six weeks of treatment, Ethambutol was removed, and the rest three drugs continued for four months. After three months of treatment, the patient had fully recovered: no swelling in hands and feet, no pleural effusion, no spleno-hepatomegaly, and no ascites (See ).