et al in a study on 59 cases described OFMT for the first time, as a rare deep
soft tissue tumor of uncertain differentiation predominantly occurring in the
adult male population (M: F ratio- 1.5:1). Majority of the cases
involved the lower extremities 1.
To the best of
our knowledge, no case of primary or concurrent intracranial OFMT has been
reported so far in the literature.
imaging in our case revealed an extra-axial calcified lesion along the left
cerebellar convexity appearing hypo-intense on T1 and T2, with no post contrast
enhancement, suggestive of a calcified meningioma. The lesion was hard, well
circumscribed with a broad-based attachment on gross examination.
Histopathological examination (HPE) revealed thickened durameter and fibro-collagenous
tissue showing foci of dystrophic calcification with low cellularity and
mitotic rate <2/50 high powered fields (HPF), suggestive of a "typical ossifying fibromyxoid tumor" (Figure 3). The HPE findings were consistent with the Folpe and Weiss classification of OFMT which described "typical OFMT" as those showing low nuclear grade and low cellularity and mitotic rate < 2/50 HPF 2. In contrast, malignant OFMT shows a high nuclear grade or high cellularity and mitotic activity > 2/50 HPF 2.
is a much rarer entity as compared to meningiomas which account for 14%-19% of
the primary intracranial neoplasms 3. We would like to highlight that an OFMT
lesion on imaging could masquerade as a calcified meningioma, like in this case.
malignant OFMT may be recognized histologically, a small number of otherwise
typical OFMT may behave in a clinically malignant fashion, supporting their
reclassification as tumors of intermediate malignancy
2. Recognition of malignant OFMT should
assist in the clinical management of patients with this rare soft tissue
Immunohistochemistry analysis of the ossifying fibromyxoid lesion revealed
positivity for S-100 (polyclonal, 1:800, Dako) suggesting schwannian
differentiation. This conforms to the concept of neuronal differentiation of
OFMT as laid by Folpe and Weiss 2.
We would also like to
emphasize that no case depicting the synchronous occurrence of an ossifying
fibromyxoid tumor with an intraventricular colloid cyst has been reported
earlier in the literature.
exist which explain the coexistence of multiple primary intracranial tumors of
different histogenesis in different compartments of the brain in patients
without neurocutaneous disorders or cranial radiotherapy. Gelabert et al
reported the simultaneous occurrence of a frontal lobe astrocytoma and a
colloid cyst of the third ventricle, both derived from displaced primitive
neuroectodermal cells. These cells are multipotential and may be present in
different areas of the brain. Thus, a single oncogenic factor may be
responsible for producing different tumors in the same individual 4. Another
hypothesis suggested by Karami et al, explains that this phenomenon of
simultaneous occurrence of histologically different tumors in different or same
areas of the brain could be purely coincidental 5.
There is no defined
treatment strategy regarding which lesion should be treated first, in patients
with simultaneous brain tumors. We operated the OFMT first, followed by
excision of the colloid cyst. It can be said that it is the surgeon’s
preference in corroboration with the patient profile, as to which lesion should
be dealt with first.