Orbital Infantile Myofibroma: a Case Report and Clinicopathologic Review of 24 Cases from the Literature

Isolated orbital infantile myofibroma are rare tumors in the head and neck. The mass-like clinical presentation and variable histologic features result in frequent misdiagnosis and potentially inappropriate clinical management. There are only a few reported cases in the English literature. Twenty-four patients with orbital infantile myofibroma or myofibromatosis were compiled from the English literature (Medline 1960–2011) and integrated with this case report. The patients included 14 males and 10 females, aged newborn to 10 years (mean, 34.8 months), who presented with a painless mass in the infra- or supraorbital regions, usually increasing in size andassociated with exophthalmos (n = 5). Females were on average older than their male counterparts (38.9 vs. 31.9 months, respectively; P = 0.71). The tumors were twice as frequent on the left (n = 16) than right (n = 8). Patients experienced symptoms for an average of 2.7 months before clinical presentation. The tumors involved the bone (n = 17) or the soft tissues (n = 7) of the orbit, with extension into the nasal or oral cavity (n = 3). The mean size was 3.0 cm, with a statistically significant difference between males and females (mean: 3.9 vs. 1.82; P = 0.0047), but without any differences based on age at presentation (P = 0.25), duration of symptoms (P = 0.66), or bone or soft tissue involvement (P = 0.51). Grossly, all tumors were well-circumscribed, firm to rubbery, homogenous, and white–grey. Histologically, the tumors were biphasic, showing whorled and nodular areas of fusiform cells with extracellular collagen, mixed with a population of small, primitive-appearing, darkly staining cells. Necrosis was not present, but mitoses could be seen. Tumors with immunohistochemistry performed showed strong and diffuse smooth muscle actin and vimentin immunoreactivity, but were negative with muscle specific actin, desmin, MYOD1, myogenin, S100 protein, GFAP, keratin, CD31, 34, Factor VIIIR-Ag, and CD45RB. The principle histologic differential diagnosis includes juvenile hyaline fibromatosis, fibrous hamartoma of infancy, fibromatosis coli, leiomyoma, infantile hemangiopericytoma, infantile fibrosarcoma, Ewing sarcoma/primitive neuroectodermal tumor, and lymphoma. All patients were managed with surgery. Recurrences developed in two patients at 4 and 6 months, respectively. Follow-up data was available on all but two patients (n = 22). These patients were either alive without evidence of disease (n = 18), alive but with disease (n = 3), or had died unrelated to this disease (i.e., neuroblastoma, n = 1). Orbital infantile myofibroma is a rare tumor, presenting in infancy as an enlarging mass of the orbit, with characteristic histomorphologic and immunophenotypic features. Orbital disease is usually isolated rather than part of systemic disease, and shows an excellent long-term prognosis, making appropriate separation from other conditions important.