Dear Editor

We are grateful to Dr Campodonico’s for the interest shown in our recent report of a case of chronic osteomyelitis mimicking a sarcoma.[1,2] The main point made in the letter is the need for a high level of suspicion of malignancy in unusual cases of chronic osteomyelitis (COM).

We entirely agree with this point of view. In fact, the reason for reporting the present case was that to highlight the reverse situation which is extremely unusual: COM interpreted as malignancy on clinical grounds with a large resection. The lesion described by us was completely resected and no tumour was present despite extensive sampling of the specimen (29 blocks).

Dr Campodonico also mentions in his letter that we suggested that a definitive diagnosis of COM is possible via immunohistochemical stains. This, however, was not our point. Immunohistochemistry is not diagnostic of COM but in this case served to rule out (unlikely) malignancies such as spindle cell carcinoma and spindle cell melanoma.

In conclusion, we agree with Dr Campodonico that a high index of suspicion for malignancy should be maintained in unusual cases of presumed COM. The present case, on the other hand, illustrates the reverse point, namely that a degree of suspicion should be maintained for COM in unusual cases of presumed malignancies adjacent to or involving bone.

References

(1) Campodonico F. Chronic osteomyelitis mimicking sarcoma [electronic response to C Gulmann C et al. Chronic osteomyelitis mimicking sarcoma] jclinpath.com 2003 http://jcp.bmjjournals.com/cgi/eletters/56/3/237#19

(2) C Gulmann, O Young, M Tolan, D O’Riordan, and M Leader. Chronic osteomyelitis mimicking sarcoma. J Clin Pathol 2003;56:237-239.

Dear Editor

Gulmann et al. reported on a case of chronic osteomyelitis presenting as a mass of the chest mimicking a soft tissue sarcoma.[1] The authors suggested that, although chronic osteomyelitis is a known cause of confusion with bone tumors, a definitive diagnosis is feasible by specific immunohistochemical staining. However, the potential risk of transformation of a chronic osteomyelitis in a malignant lesion is an unforgettable point either for the clinician or the pathologist.[2] Two years ago, I encountered a patient developing a rapidly aggressive sarcoma with an uncommon onset. He was a 23-year-old man, with a sixteen-month history of chronic osteomyelitis of the left hip bone, referred to urologic department. Three years before, he had been involved in a road accident with a bilateral fracture of the thigh bone and left acetabulum. On admission to the ward the patient reported fever, dysuria and suprapubic pain. Physical examination demonstrated an osteocutaneous fistula with smelling drainage on the lateral aspect of the left hip bone. On standard computed tomography an haemorragic mass causing bladder impression and connected with the fistula was observed. A surgical exploration was performed with drainage of septic tissue and a 5 cm pelvic lymph node was excised from the left iliac chain for histological examination. Light microscopy showed a solid proliferation of spindle- shaped cells, with a high mitotic index, associated with lymphatic aggregates and foci of necrotic tissue. Staining for S-100 protein, desmine, vimentine and focal smooth actine were positive. The histological and immunohistochemical features of the pelvic node confirmed an undifferentiated sarcoma. The patient died three months postoperatively. Malignant lesions are rare complications of chronic osteomyelitis. As reported in a large serie by McGrory et al,[3] squamous cell carcinoma is by far the most common type of associated malignant disease, while sarcoma has been exceptionally reported.[4] The latency period between onset of osteomyelitis and development of neoplasia may be as short as 1 year ot it may be decades. Generally the neoplasia occurs in the osteomyelitic sinus or in a chronic draining fistula. The most frequent clinical findings of malignancy in chronic fistulating osteomyelitis are persistent foul discharge, pain and bleeding.[3] In this case, the osteocutaneous fistula was connected to the left iliac area where the sarcoma arised and spread to pelvic lymph nodes. In conclusion, even though chronic osteomyelitis may be a cause of difficult diagnosis with bone tumors, I would emphasize the need to mantain an high index of suspicious in case of chronic osteomyelitis with an unusual presentation.

References

(1) Gulmann C,Young O,Tolan M,O'Riordan D,Leader M. Chronic osteomyelitis mimicking sarcoma. J Clin Pathol 2003;56:237-9

(2) Slominski A, Wortsman J, Carlson A, Mihm M, Nickoloff B, McClatchey KD. Molecular pathology of soft tissue and bone tumors. A review. Arch Pathol Lab Med 1999;123:1246-59

(3) McGrory JE,Pritchard DJ,Unni KK et al. Malignant lesions arising in chronic osteomyelitis. Clin Orthop 1999;362:181-9.

(4) Akbarnia BA,Wirth CR,Colman N. Fibrosarcoma arising from chronic osteomyelitis. Case report and review of the literature. J Bone Joint Surg Am 1976;58:123-5.