Right arm pyomyositis and necrotizing fasciitis complicated with subcutaneous emphysema and pneumomediastinum in a patient with diabetes mellitus and iatrogenic cushing syndrome.

Abstract: We report a case of subcutaneous emphysema and pneumomediastinum secondary to pyomyositis and necrotizing fasciitis over the right arm of a woman with underlying diabetes mellitus and iatrogenic Cushing syndrome. Gas produced by the culprit pathogen extensively dissected the subcutaneous fat and fascia of the patient's right arm and distantly spread to her face, neck, back, and thoracic wall and penetrated the soft tissue cephalically bordering her sternum, resulting in pneumomediastinum. The patient improved with antimicrobial therapy and localized debridement and fasciotomy over her right arm.

Key Words: diabetes mellitus, iatrogenic Cushing syndrome, necrotizing fasciitis, pneumomediastinum, pyomyositis

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Subcutaneous emphysema in the face and neck and pneumomediastinum are uncommon complications of trauma to facial bones, trachea-bronchial tears, esophageal laceration, radical neck dissection, and dental extraction. (1-3) Pneumomediastinum may also result from air entering the mediastinum through the retroperitoneal space. (4) We herein report a case of subcutaneous emphysema and pneumomediastinum resulting from necrotizing fasciitis and pyomyositis over the right arm of a woman with diabetes mellitus and iatrogenic Cushing syndrome. The clinical implications of the case are also discussed.

Case Report

A 64-year-old diabetic woman presented to our Emergency Service with a progressively swelling right forearm, accompanied by some overlying vesicles of 2 days' age. The patient had a history of using analgesics and steroids for her low back pain and bilateral knee arthralgia. She repeatedly had carbuncles over her right elbow in the previous 5 years. Upon arrival, the patient was found to have tachycardia and to be in respiratory distress. Physical examination revealed a Cushingoid habitus (puffy face, buffalo hump, central obesity, and paper-thin skin) and a painful erythematous swelling of the right upper limb with overlying hemorrhagic bullae. Tactile crepitus was found over her right hind arm, which distantly extended to her neck, back, and thoracic wall. The patient's phonation was normal. Chest radiography showed a shaggy appearance over the tactile crepitus area and air streaks distributed in a longitudinal fashion in the mediastinum, which were suggestive of an extensive subcutaneous emphysema and pneumomediastinum. A CT scan revealed pneumomediastinum (Figure). A diagnosis of gas-producing pyomyositis and necrotizing fasciitis over the right upper limb complicated with the pneumomediastinum was made. However, pyogenic mediastinitis could not be excluded. After drawing blood for culture, broad-spectrum antibiotic coverage with ceftazidime, gentamicin, and clindamycin was started. The patient's severe immunoincompetence and critical septic condition raised concern about whether or not she was able to tolerate an extensive emergency operation including exploration of the mediastinum. Therefore, a localized debridement and fasciotomy over the right arm was performed. The subsequent esophagogram and bronchoscopic study revealed no evidence of esophagus rupture or trachea-bronchial mucosa tears. The pus taken during operation was sent for culture, which subsequently grew cefazolin-susceptible Escherichia coli and Proteus vulgaris, methicillin-susceptible Staphylococcus aureus, group-B streptococcus, and Peptostreptococcus species. Blood culture was negative. Antibiotics were switched to cefazolin alone, based on the assumption that E coli was the most likely culprit pathogen for the massively produced gas and that the remaining bacteria were either local colonizing microbes or pathogens causing minor localized soft tissue infection.

The patient's condition progressively improved. A radiograph 2 weeks later revealed that the subcutaneous emphysema and pneumomediastinum had resolved. Antibiotic therapy was continued for 6 weeks, and a skin graft was performed over the surgical site before discharge from our hospital.

Discussion

Pneumomediastinum resulting from different causes may require different treatments. Pneumomediastinum secondary to esophageal or trachea-bronchial rupture (3) or infra-diaphragm infection spreading through retroperitoneum (4) in addition to antimicrobial therapy requires surgical treatment or drainage. On the other hand, pneumomediastinum resulting from air driven into the subcutaneous tissue and mediastinum, such as improper central venous placement or use of high-speed air-driven dental drill, can be expected to improve by supportive treatment and antibiotic prophylaxis. (3)

Once the air iatrogenically driven into the soft tissue is compressed highly enough, it will dissect the less-resistant subcutaneous fat and fascia plane, spreading to distant sites. (5) The air in the soft tissue of the right arm of this patient was produced by E coli, S aureus, or both. Diabetic patients in the advanced stage often have an impaired immune function, (6) and their atherosclerosis-associated poor tissue circulation and elevated tissue glucose levels establish an environment low in oxygen tension and rich in substrates for bacterial growth, (7) especially Enterobacteriaceae. (8) As a result, E coli probably was the pathogen responsible for the massive gas production in this patient. The unique presentation in this case is that the subcutaneous emphysema was so extensive that the gas traversed the thoracic wall and penetrated the connective tissue cephalically bordering the sternum, entering the mediastinum. We believe that it was because of the underlying, easily torn, fragile connective tissue associated with iatrogenic Cushing syndrome. (9)

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Necrotizing fasciitis requires antimicrobial therapy and surgical debridement. The earlier the intervention, the better the prognosis. (10) Unfortunately, the paucity of skin findings often makes an early diagnosis of necrotizing fasciitis difficult if not impossible. The presence of gas in the soft tissue detected clinically or radiologically is an important clue to necrotizing fasciitis, but its absence does not exclude necrotizing fasciitis. (7)

Conclusion

This case demonstrates the unusual complications of pyomyositis and necrotizing fasciitis in a severely immunocompromised patient.

The secret of success is to know something nobody else knows.
--Aristotle Onassis

Accepted May 4, 2004.

References

1. Harvey-Smith W, Bush W, Northrop C. Traumatic bronchial rupture. Am J Roentgenol 1980;134:1189-1193.

2. Minton G, Tu HK. Pneumomediastinum, pneumothorax and cervical emphysema following mandibular fracture. Oral Surg Oral Med Oral Pathol 1984;57:490-493.

3. Chen SC, Lin FY, Chang KJ. Subcutaneous emphysema and pneumomediastinum after dental extraction. Am J Emerg Med 1999;17:678-680.

4. Ripetti V, Caricato M, Arullani A. Rectal perforation, retropneumoperitoneum, and pneumomediastinum after stapling procedure for prolapsed hemorrhoids: report of a case and subsequent considerations. Dis Colon Rectum 2002;45:268-270.

5. Rossiter JL, Hendrix RA. Iatrogenic subcutaneous cervicofacial and mediastinal emphysema. J Otolaryngol 1991;20:315-319.

6. Nolan CM, Beaty HN, Bagdade JD. Further characterization of the impaired bactericidal function of granulocytes in patients with poorly controlled diabetes. Diabetes 1978;27:889-894.

7. Green RJ, Dafoe DC, Raffin TA. Necrotizing fasciitis. Chest 1996;110:219-229.

8. Mahon C, Manuselis G. Enterobacteriaceae, in Mahon C, Manuselis G (eds): Textbook of Diagnostic Microbiology. 2nd ed. Philadelphia, WB Saunders Company, 2000, pp 463-511.

9. Guyton AC, Hall JE. Human Physiology and Mechanisms of Disease. 6th ed. Philadelphia. WB Saunders Company, 1997.

10. Bilton BD, Zibari GB, McMillan RW, et al. Aggressive surgical management of necrotizing fasciitis serves to decrease mortality: a retrospective study. Am Surg 1998;64:397-401.

RELATED ARTICLE: Key Points

* Pyomyositis and necrotizing fasciitis of the right arm led to subcutaneous emphysema and pneumomediastinum in a diabetic patient with iatrogenic Cushing syndrome.

* Localized debridement and fasciotomy over the right arm coupled with antibiotic therapy cured the patient, and the pneumomediastinum disappeared.

Chen-Hsiang Lee, MD, and Jien-Wei Liu, MD

From the Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Taiwan, Republic of China.

Reprint requests to Dr Jien-Wei Liu, Division of Infectious Diseases, Department of Internal Medicine, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Taiwan, 123, Ta Pei Road, Niao Sung Hsiang, Kasohsiung Hsien, Taiwan 833, ROC. Email: [e-mail]