Letter to the Editor: Pseudomalignant myositis ossificans mimicking osteosarcoma: a case report

Journal of Orthopaedic Surgery, Dec 2006 by Khan, S A, Kumar, A, Ragunanthan, N, Sugavanam, C

To the Editor:

We read with interest the case report by Ragunanthan and Sugavanam.1 We are not completely convinced by the way in which the diagnosis and management was undertaken. Firstly there was a paucity of imaging pictures in the report. Radiographs and magnetic resonance images would have greatly enhanced readers' knowledge. In our opinion a computed tomography (CT) scan of the thigh would have been very useful as it could have shown zonation, a characteristic radiological feature of myositis ossificans. In fact, the importance of imaging (especially CT) in the diagnosis of pseudomalignant myositis ossificans has been stressed in the liter-ature.2-4 Secondly, if a diagnosis of osteosarcoma was made in the first place, why was the patient not subjected to a 3-pool bone scan to rule out metastatic disease? A bone scan is also known to supplement the diagnosis of myositits ossificans.5 To confirm the diagnosis of osteosarcoma, a core or a tru-cut biopsy (CT-guided) would have been a better option than excisional biopsy, which is relatively contra-indicated in suspected malignant lesions. The authors also failed to detail the chemotherapy regimen (consisting of adriamycin and cisplatin), which was used initially for suspected osteosarcoma.

We feel that the report could have been more useful to readers if the abovementioned lacunae were filled. However, we congratulate the authors for focusing on an important diagnostic problem, occasionally encountered in orthopaedic oncology.

REFERENCES

1. Ragunanthan N, Sugavanam C. Pseudomalignant myositis ossificans mimicking osteosarcoma: a case report. J Orthop Surg (Hong Kong) 2006;14:219-21.

2. De Santis E, Rosa MA, Gasparini G. Circumscribed spontaneous heterotopic ossification in the soft tissues simulating sarcoma. Ital J Orthop Traumatol 1987;13:207-17.

3. Nuovo MA, Norman A, Chumas J, Ackerman LV. Myositis ossificans with atypical clinical, radiographic, or pathologic findings: a review of 23 cases. Skeletal Radiol 1992;21:87-101.

4. Spina V, Montanari N, Romagnoli R. Malignant tumors of the osteogenic matrix. Eur J Radiol 1998;27(Suppl 1):S98-S109.

5. Shih WJ, Hackett MT, Stipp V, Gross K, Pulmano C. Myositis ossificans demonstrated by positive gallium-67 and technetium-99m-HMDP bone imaging but negative technetium-99m-MIBI imaging. J Nucl Med Technol 1999;27:48-50.

SA Khan

A Kumar

Department of Orthopaedics

All India Institute of Medical Sciences

Ansari Nagar, New Delhi

India

Authors' reply

Radiographs and magnetic resonance images were not published for want of space. Magnetic resonance imaging is superior to computed tomography for detection of a soft tissue mass. Hence computed tomography was not considered in our preoperative investigations.

The diagnosis of osteosarcoma was not made before the biopsy. Open biopsy was performed rather than fine-needle aspiratory cytology or needle biopsy, because the accuracy of the latter techniques varies between 65% and 80% in unsuspected soft tissue lesions. Moreover, a specialist musculoskeletal pathologist is needed to analyse the tissue specimens. Open biopsy has been proved more accurate and safe if guidelines are followed meticulously.

Details of chemotherapy were not mentioned as they were not relevant to the discussion. The point we wished to highlight was the diagnostic difficulty in such cases.

N Ragunanthan

C Sugavanam

Department of Trauma and Orthopaedics

Kovai Medical Centre and Hospital

Coimbatore, India