Secondary Erythromelalgia - A Case Report -
A 48-year-old woman visited our pain clinic for 2-year episodes of the right hand and wrist pain with a pain score of 9-10/10 by VNRS (verbal numeric rating scale; 0 with no pain, 10 with maximal pain). She had been to several local clinics. Each time she had been diagnosed with different conditions, such as rheumatic arthritis, Raynaud's phenomenon, and other musculoskeletal diseases. They prescribed painkillers such as acetaminophen, tramadol, pregabalin and even alprazolam along with various physical therapies, but her pain became worse so that she could not even do her house work. The pain started with a sudden onset of "burning" as she described it. It started with her right hand then spread to her wrist. It seemed to worsen whenever she took a bath. Her right hand including all of her fingers seemed red and slightly swollen. No tenderness and warmth were detected. Other parts of her body including the left hand were not involved. Her vital signs including blood pressure were normal and she had no co-existing diseases such as hypertension or diabetes. She recalled no traumatic event happening to the affected area. X-ray findings showed no bony abnormalities. Electromyography and nerve conduction studies of both upper extremities were normal and showed no evidence of peripheral neuropathy. Infrared thermography studies were performed to assist in understanding the patient's disorder. In the resulting images, the affected areas of her upper extremities appeared red, indicating a higher temperature, while other areas appeared yellow or green, indicating a lower temperature; this visualization also revealed vascular markings in the affected hand. The difference in temperature for the region of interest (ROI) was 2.35℃ (35.37℃ vs 33.02℃) at the most differentiable area in the third and fourth fingers ().\nLaboratory tests were performed including CBC (complete blood count) with differential and platelet counts. Initial red blood cell count was 4.84 × 106/µl; white blood cell (WBC) count was 8.3 × 103/µl; hemoglobin level was 13.8 g/dl; hematocrit was 41.7%, and platelet count was 1,131,000/mm3. Prothrombin time (PT) and partial thromboplastin time (aPTT) were 11.3 seconds and 31.2 seconds, respectively. Erythrocyte sedimentation rate (ESR), rheumatoid factor (RF), and antinuclear antibody (ANA) screening data were within the normal range.\nWe treated her with 500 mg of aspirin per day, and transferred her to a hematologist for further evaluation. She was diagnosed with essential thrombocytosis after a bone marrow biopsy and aspiration study, and chemotherapy was started with anagrelide while continuing to administer a low dose of aspirin (100 mg per day).\nA month later, her platelet count measured 340,000/mm3, and her symptoms dramatically disappeared with a pain score of 1/10 (VNRS). Infrared thermography studies also showed a remarkable change. The temperature had decreased in the affected areas, where the color was now yellow; the color boundary between the affected area and the remaining areas was negligible, and the temperature was similar to that of the unaffected arm.