Statistics from Altmetric.com
A rare case of solitary interhemispheric myofibroma with excellent outcome in a 20 month old boy is described. The clinicopathological features of this unusual condition are reviewed with emphasis on the CNS manifestations.
A case of congenital fibrosarcoma was first diagnosed by William and Schrum1 and was subsequently renamed congenital generalised fibromatosis by Stout in 19542 as a distinct form of juvenile fibromatosis characterised by tumour-like nodules involving the skin, soft tissues, bones, and viscera. Based on the ultrastructural and immunohistochemical features of the cell of origin and the occurrence of this condition in infants, as well as congenitally, it was renamed infantile myofibromatosis by Chung and Enzinger in 1981.3 This disorder is considered to represent a hamartomatous myofibroblastic proliferation, although laboratory evidence suggests that it may arise secondary to oestrogen stimulation in utero. Infantile myofibromatosis represents the most common fibrous tumour of infancy and may present with solitary or multicentric lesions. When visceral involvement is present, the multilesional form is termed “generalised”. Cases with familial incidence,3spontaneous regression,4 5 and fatal outcome3 6 have all been described. Poor outcome has generally been associated with extensive visceral involvement and relates either to mass effect with compression of vital organs and structures, or to pulmonary involvement, when subintimal or submucosal cellular proliferation results in vascular or bronchial obliteration.2
Central nervous system involvement is exceptionally rare and has been reported as a finding in the multicentric type of myofibromatosis.6-9 We describe a solitary interhemispheric myofibroma which presented as an intracranial mass in a 20 month old child. To our knowledge, only one other case of solitary intracranial myofibroma has been reported.10
A 20 month old Irish boy, the only son of healthy, unrelated parents, was admitted for investigation of a large head. He had one previous hospital admission at the age of 6 weeks for a respiratory tract infection. Transient muscle hypotonia was noted at that time as was his skull circumference of 43 cm. At 6 months there was no hypotonia, neurological examination was normal, and the head circumference was 49 cm. The father’s head circumference was 61 cm and he stated that all of his family had “big heads”. By 20 months, the patient’s head circumference measured 55.6 cm and was diverging from the 97th centile. Brain CT showed a well circumscribed, contrast enhancing mass in the midline and left frontal lobe, with surrounding oedema. There was evidence of left sided hydrocephalus due to displacement of the right foramen of Munro by tumour. The radiological differential diagnosis included a primary meningeal tumour, glioma, and leukaemic deposit. The patient underwent a left frontal craniotomy and a firm, rounded mass was removed from between the hemispheres. The mass was not attached to the falx, but was firmly adherent to the left pericallosal artery. A fragment (4 mm×2 mm) had to be left attached to the vessel. Postoperatively, he had transient paresis of the right leg, which subsequently resolved completely. Repeat CT 6 months later and at 4 years after the operation showed no evidence of recurrence or mass effect. His head circumference persisted on the 97th centile 4 years after operation. His development and clinical examination otherwise remain normal 6 years after surgery. A younger sibling is normal.
The rounded 3.0 cm mass had a whorled, fibrous, white-yellow cut surface appearance. Microscopically, it consisted of hypercellular fasciculated and storiform areas, alternating with hypocellular, hyalinised regions. Centrally a haemangiopericytoma-like pattern was seen. No mitotic figures were present and there was no evidence of haemorrhage, necrosis, or calcification. The tumour cells appeared to blend with the vessel walls. Immunohistochemical studies showed strong reactivity for vimentin and smooth muscle actin. Scattered cells showed immunoreactivity for desmin. No reactivity was noted for cytokeratin, epithelial membrane antigen, factor VIII, glial fibrillary acidic protein, or myoglobin. Ultrastructural examination showed elongated cells with surrounding collagen fibrils, some showing intracytoplasmic myofilaments.
Solitary lesions of infantile myofibromatosis are more common than multiple lesions, with twice as many males as females being afflicted, and generally involve the skin and soft tissues, especially of the head and neck.2 Solitary lesions are less commonly found in viscera or bones.11 Involvement of the CNS is exceedingly rare and only one other case of a solitary mass is reported10 along with few cases of CNS involvement in the generalised form of infantile myofibromatosis.6-9 11-13The prognosis is best for cases with solitary masses and less favourable for multicentric cases, particularly where visceral lesions are present, in which morbidity and mortality derive predominantly from pulmonary involvement or mass effect.
The differential diagnosis for this lesion included meningioma, schwannoma, and haemangiopericytoma. Regionally, the histology was reminiscent of the rare microcystic variant of meningioma. Meningiomas are extremely rare in this age group, this lesion was not meningeal based and such lesions are usually reactive for epithelial membrane antigen unlike this tumour. This lesion, unlike schwannomas, showed no immunoreactivity for S-100 protein. Haemangiopericytoma is a diagnosis of exclusion and shows no reactivity for actin, unlike this tumour.
Prior reports of intracranial involvement by myofibromatosis include patients with widespread systemic involvement and multiple leptomeningeal nodules6 in one patient and extradural masses in another,8 both of which were fatal at the age of 10 days, a non-fatal7 extradural mass in one patient, and a patient with systemic involvement, in which there was recurrence of orbital and temporal lesions 2 years after operation. A single previous case of solitary intracranial myofibroma has been reported10 in which the patient died within 24 hours of surgery, secondary to cardiorespiratory arrest.
We present a patient with a solitary intracranial myofibroma with an excellent postoperative outcome. Although rare, infantile myofibroma should be included in the differential diagnosis of intracranial neoplasms in children.
We acknowledge the expert assistance of Drs Lucy Roarke and Dr Louis Dehner in diagnosing this case.
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.