Paravertebral Osteolipoma.

Dear Editor,

We read with great interest the case report entitled "Cervical paravertebral osteolipoma: case report and literature review" in the issue of Asian Spine J 2015;9(2):290-4 [1]. We would like to congratulate the authors for their analysis of this complex and challenging case.

However, we have some concerns regarding the case report and wish to share them. Osteolipoma, a lipoma with osseous metaplasia, is a very rare histological variant accounting for less than 1% of all lipomas [234]. It is seen in many anatomic sites, including the scapula, vertebral spine, neck, skull, suprasellar region, and tuber cinereum [234].

The differential diagnosis of osteolipoma also includes liposarcoma which is not mentioned in the article. Results of magnetic resonance imaging evaluation of 126 consecutive fatty masses by Gaskin and Helms [5] showed that osteolipoma may mimic well-differentiated liposarcomas, from which they are often hard to differentiate on imaging alone. Differentiation and definitive diagnosis of the osteolipoma can be done with histopathologic examination and treatment is by surgical excision. In addition, the identification of histological subtypes in already known variants of lipoma, such as low-fat and fat free spindle cell lipomas, highlight the importance for careful microscopic evaluation of these tumors [1234].

As a conclusion we are of the opinion that the diagnosis of osteolipoma is not straightforward, and complete surgical resection is the treatment of choice. Like conventional lipomas, the prognosis of osteolipoma is favorable, but lesions should be monitored carefully and postoperative close monitoring with long-term follow-up is recommended, as there is only a minority of relevant clinical information about this rare tumor.

Again we appreciate the authors' work, which adds to our knowledge of this difficult clinical problem.