Intraosseous infantile myofibroma of the mandible
A 10-month-old boy was referred to Department of Maxillofacial Surgery with a painless swelling in the mandibular left posterior region that had been present for 5 months. The lesion had gradually increased in size. Medical and familial histories were noncontributory. There was no history of trauma or spontaneous bleeding associated with the lesion. No lymph nodes were palpable in relation to the lesion. An extraoral examination showed a diffuse swelling, firm in consistency, approximately 3 × 3 cm, extending from the angle of the mandible to the middle of the ramus and superoinferiorly from 2 cm below the malar prominence to the inferior border of the mandible []. There was no extraoral discharging sinus and the skin over the lesion appeared normal. Intraoral examination showed an expansile mass involving buccal and lingual cortices in the retromolar and molar region.\nThe two-dimensional (2D) CT scans [Figures and ] showed a lesion approximately 2.7 × 2.1 cm in the posterior mandible on the left side with broad expansion of the buccal and lingual cortices and well-defined borders. The mass showed central soft tissue attenuation and well-defined borders. Bony erosion at the margins was also seen. Further analysis of the 3D CT confirmed the extent of the lesion and also revealed areas of bone destruction in the buccal and lingual cortices. It also showed infringement of the lesion up till the coronoid and condylar process.\nIncisional biopsy established the diagnosis of myofibroma, and complete surgical excision along with a peripheral osteotomy was planned.\nUnder general anesthesia, nasotrachael intubation was done. After infiltrating with local anesthesia, the mucoperiosteal flap was raised and the lesion was exposed. The lesion was excised and a margin of normal bone of 1 cm, surrounding the lesion, was also removed. The inferior alveolar nerve was found to be displaced and was not damaged during the resection. The mass was removed in fragments from the bony crypt and was found to be unencapsulated. Thorough curretage of the bony crypt was carried out; gelfoam was used to fill the defect []. Postoperative recovery was uneventful. A 15-month follow-up period showed no signs of recurrence. Pre- and postoperative assessment of the inferior alveolar nerve could not be carried out accurately due to the age of the child.\nThe excised mass was sent for histopathological analysis. The macroscopic presentation was that of multiple fragments of greyish white soft tissue, the largest measuring 2.5 × 1 × 0.8 cm and the smallest measuring 8 × 3 × 2 mm. The cut surface had a firm white appearance. Microscopic examination confirmed the mass as myofibroma and the histologic picture revealed the typical biphasic pattern with spindle cells, which were arranged in fascicles and bundles. The nuclei were spindle shaped with bright eosinophilic cytoplasm set in hyalinized stroma with a faint basophilic appearance. One section showed an area of hyalinization. Focally congested blood vessels and a cluster of foreign body-type multinucleate giant cells were seen. Fragments of bone were also seen on one aspect. A concomitant characteristic trait of a hemangiopericytoid pattern, i.e., a combination of smaller cells and slit-like vascular spaces, was prominent. The mitotic activity was absent.\nImmunohistochemical analysis confirmed the diagnosis. The specimen tested positive for smooth muscle actin and vimentin [Figures and ]. Immunoreactivity for cytokeratin, desmin, and S-100 protein were negative.