A neuromuscular hamartoma is a rare benign tumour that is most frequently associated with peripheral nerves. The authors present a case of a 61 year-old man with bilateral exophthalmos and lid retraction who developed further proptosis and chemosis in the left eye over a five month period. An initial diagnosis of thyroid orbitopathy was made and he had a limited response to two courses of oral steroid administered in another centre. He was subsequently referred to our institution for further management when his condition worsened following withdrawal of treatment. Orbital CT scan showed a thickening of the recti muscles and particularly the left superior rectus and overlying soft tissue. Given this unusual pattern of muscle involvement in thyroid orbitopathy, a muscle biopsy was performed. This showed the presence of a neuromuscular hamartoma without malignant features. The orbital fat biopsy showed no pathological findings. A neuromuscular hamartoma not associated with a peripheral nerve is a rare entity, especially when coupled with an extraocular muscle. We wish to highlight the importance of a muscle biopsy when faced with a clinical picture and radiological pattern of extraocular muscle enlargement not typical of what we know to occur traditionally in thyroid eye disease.
[Show abstract][Hide abstract] ABSTRACT: Neuromuscular hamartoma (choristoma) or benign "triton" tumor is a very rare peripheral-nerve tumor composed of mature nerve fibers and well-differentiated striated muscle fibers. Only seven cases have been reported in the literature. A new case of this rare entity is described in a 36-year-old white woman with a recurrent left supraclavicular mass in the brachial plexus area. Unlike the previous cases, this patient had continued to have proliferation of her tumor since childhood, requiring total resection in adulthood. It is concluded that total resection of these tumors should be attempted at initial diagnosis. The histogenesis of these tumors remains unclear. They may represent proliferation of neuroectodermal-derived or limb mesodermal tissue in the elements of a peripheral nerve.
Journal of Neurosurgery 12/1991; 75(5):795-7. DOI:10.3171/jns.1991.75.5.0795 · 3.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Neuromuscular choristoma (NMC) is a rare peripheral nerve lesion in which mature skeletal muscle fibers lie within the nerve and its fascicles. Given limited follow-up, its natural history is poorly understood. The occurrence of aggressive fibromatosis in one of the authors' patients and its occurrence in reported cases suggests an etiological relationship between the 2 lesions. This study attempts to explain the association and its frequency.
All cases of NMCs seen in consultation or treated at the Mayo Clinic were identified. Demographic and clinical data were reviewed in cases with coexistent aggressive fibromatosis. Pathology and neuroimaging studies were reexamined. In addition, an extensive literature review was performed to explore the association of NMC with aggressive fibromatosis, with special attention given to pathological and imaging characteristics and the development of aggressive fibromatosis.
The authors identified 10 patients with a diagnosis of NMC who were treated at the Mayo Clinic between 1992 and 2010. Four of 5 with adequate follow-up had developed a definite or suspected aggressive fibromatosis. A review of the initial pathological specimens in these cases revealed no evidence of fibromatosis, but all of the lesions exhibited accompanying hypocellular collagenous tissue. On MR images, all cases showed areas of low signal intensity, which significantly differed from muscle, nerve, and NMC components. On available serial MR imaging studies, aggressive fibromatosis seemed to originate in such lower-intensity regions. In the 18 previously reported cases of NMC, 5 patients developed recurrent masses diagnosed as either definite (2 cases) or possible (3 cases) fibromatosis. Review of the published imaging studies in these cases suggests the presence of lower intensity areas similar to those observed in the 10 patients treated at the Mayo Clinic.
This study confirms that the development of aggressive fibromatosis in patients with NMC has been underreported. A direct relationship between the NMC and the development of aggressive fibromatosis is suggested by pathological and neuroimaging evidence.
Journal of Neurosurgery 08/2011; 116(2):399-408. DOI:10.3171/2011.6.JNS102171 · 3.74 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Orbital malignancy can mimic thyroid associated orbitopathy (TAO) due to overlap of clinical and radiographic findings, which include proptosis, extraocular muscle (EOM) enlargement on imaging, and EOM restriction with diplopia. We report a case of primary orbital liposarcoma masquerading as TAO which required exenteration.
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