Grade 2 primary myxofibrosarcoma of calvaria: first case report in literature

Introduction: A 43-year-old female went to a medical appointment in Caxias do Sul, Rio Grande do Sul, Brazil, in November 2012, presenting with left hemicrania. There were no apparent neurological deficits and no comorbidities. A computed tomography (CT) of the head showed a lesion of the left parieto-occipital region of the calvaria. In 2013, it was performed a resection of the lesion. The histopathology and immunohistochemistry of the lesion were consistent with grade 2 myxofibrosarcoma of the calvaria and adjuvant radiotherapy sessions were administered, with a total dose of 60 Gy. In order to monitor the patient, periodic CTs and magnetic resonance imaging of the head were performed. In 2017, the patient referred again a similar left hemicrania, consistent with local recurrence of the tumor in the calvaria. Again, surgical resection of the lesion was performed, accompanied by bone reconstruction. In 2018, the patient is asymptomatic with no evidence of tumor recurrence or metastasis.

Discussion: Primary bone tumors are responsible, approximately, for 0.2% of all malignancies. The skull site is uncommon, although it is strongly related to multiple myeloma. Moreover, myxofibrosarcomas of the bone are extremely rare. To the authors’ knowledge, there are only five cases of myxofibrosarcomas arising from bone in the literature. However, this incidence may be underestimated, since some other reports aren’t clear whether the myxofibrosarcoma is primarily from bone or is an invasion from tumors of adjacent soft tissues. All of the five cases reported in literature involved lower limbs, occurring at ages of 39–68 years, with a male/female ratio of 3:2. When reported, the main clinical feature was a painful swollen knee. In two cases, surgical resection was performed, with no evidence of local recurrence or metastasis after one year of follow up in one case. In the other cases, follow-up and/or treatment approach were not reported. Here, the authors present the first case of a myxofibrosarcoma arising primarily from the calvaria.

Final commentaries: This is the first case report of a primary myxofibrosarcoma of calvaria in literature. Although extremely rare, this condition should be considered as a differential diagnosis of other tumors in calvaria.

No conflict of interest has been declared by the author(s).