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- Diff Dx: Painful Joint:
    - four conditions may cause an excruciatingly painful joint;
         - infection
         - Gout or, rarely, Pseudogout;
         - Rheumatic Fever;
         - Tumor;
- Diff Dx Tumor:
    - osteoid osteoma
    - Osteosarcoma
    - chondrosarcoma
    - Chondroblastoma
    - Fibrosarcoma of bone
    - Fibrous Dysplasia
    - Giant Cell Tumor of Bone
    - Eosinophilic granuloma
    - Ewing's sarcoma
    - Reticulum cell sarcoma
- Discussion: Painful Tumors:
    - clinical features associated with bone tumors include pain, deformity, and impairment of function;
    - pain is feature common to almost all malignant tumors of bone, but may or may not be present in benign lesions;
    - malignant bone tumors are usually associated with deep, aching pain, which, although not sharp and sometimes not severe, is quite
         distressing to the patient because of its constancy;
    - pain that persists at night and is not relieved by rest is suggestive of malignancy; however, certain benign tumors, such as osteoid osteoma,
         are characterized by nocturnal pain;
    - mild, dull, aching back pain that suddenly becomes excruciating w/ such insignificant trauma as sitting down a bit hard suggests pathologic 
         compression frx in vertebra involved by metastatic cancer