Benign Triton Tumor Research Articles

Lipomatosis of Nerve and Neuromuscular Choristoma: Two Rare Entities and Their Call for an Animal Model to Understand and Mitigate Nerve-Territory Sequelae

Two rare congenital nerve conditions (lipomatosis of nerve (LN) and neuromuscular choristoma (NMC)) share certain commonalities (hypertrophic fusiform lesions, often presenting with neuropathy in adolescent ages and an association with other lesions), but also have important clinical differences (nerve-territory overgrowth and undergrowth, respectively). LN is part of a spectrum of adipose tissue proliferations that affect nerves. NMCs, previously known as benign Triton tumors, are lesions in which mature skeletal muscle is admixed with nerve fascicles. Recent advances have led to the description of classic clinicoradiologic features and the identification of distinct genetic alterations in LN and NMC, that have direct clinical implications and present potential research opportunities for these and other related conditions.

Pediatric Benign Tumors With a Skeletal Muscle Component: Myogenin Expression, Diagnostic Pitfalls, and New Molecular Insights.

Benign tumors with skeletal muscle differentiation are rare and their characterization in the literature is limited. We present a series of twelve pediatric benign tumors with rhabdomyomatous differentiation including seven rhabdomyomatous mesenchymal hamartomas, four fetal rhabdomyomas, and one benign triton tumor, analyzing myogenic markers as well as clinicopathologic and molecular features. A review of the literature was also performed with an emphasis on myogenic marker expression and correlation with molecular features. Cases obtained from three tertiary pediatric hospitals were retrospectively reviewed. Eleven of twelve cases expressed myogenin in rare to greater than 15% of cells. Five of nine cases had rare to 70-80% of cells positive for MyoD1. One fetal rhabdomyoma demonstrated homozygous deletions in ZEB2. The benign triton tumor harbored a CTNNB1 mutation. Review of the literature identified 160 pediatric benign tumors with skeletal muscle differentiation of which 9 reported myogenin positivity. Myogenin and MyoD1 may be variably expressed in benign lesions with skeletal muscle differentiation. Recognition of key morphologic features remains critical to diagnose these lesions and, in rhabdomyoma, to exclude malignancy. Our series expands the knowledge of the relationship between rhabdomyoma and rhabdomyosarcoma (RMS) by identifying a shared molecular alteration in ZEB2.

Peripheral Nerve Sheath Tumors of Head and Neck: Imaging-Based Review of World Health Organization Classification.

We aim to review the imaging appearance of peripheral nerve sheath tumors (PNSTs) of head and neck according to updated fourth edition of World Health Organization classification. Peripheral nerve sheath tumor can be sporadic or associated with neurofibromatosis type 1, neurofibromatosis type 2, and schwannomatosis. Schwannoma is the most common benign PNST that can be intracranial or extracranial and appears heterogeneous reflecting its histologic composition. Melanotic schwannoma is a different entity with high prediction of malignancy; it shows hypointense signal on T2-weighted image. Neurofibroma can present by localized, plexiform, or diffuse lesion. It usually appears homogeneous or shows a characteristic target sign. Perineurioma can be intraneural seen with the nerve fiber or extraneural appearing as a mass. Solitary circumscribed neuroma and neurothekeoma commonly present as dermal lesions. Nerve sheath myxoma may exhibit high signal on T1 weighted image. Benign triton tumors can be central, aggressive lesion, or peripheral nonaggressive lesion. Granular cell tumor shows hypointense signal on T2 weighted image. Neuroglial heterotopia most commonly occurs in the nasal cavity. Ectopic meningioma arises from ectopic arachnoid cells in the neck. In hybrid PNST, combined histological features of benign PNST occur in the same lesion. Malignant PNSTs are rare with an aggressive pattern. Computed tomography and magnetic resonance imaging are complementary studies to determine the location and extent of the tumor. Advanced magnetic resonance sequences, namely, diffusion-weighted imaging and dynamic contrast enhancement, can help in differentiation of benign from malignant PNST.

Hamartome neuromusculaire de l’orbite : rapport d’un cas et discussion de la place de corticothérapie dans le traitement

Neuromuscular hamartoma, also known as neuromuscular choristoma or benign triton tumor, is a rare benign tumor of well-differentiated striated muscle fibers mixed with peripheral nerve fibers. According to our research, this is the sixth case of benign triton tumor of the trigeminal nerve and the third case of isolated orbital location reported in the world literature. To report a rare case of orbital neuromuscular hamartoma and discuss the role of corticosteroids in the treatment of these lesions for which surgical excision is often difficult. A 47-year-old woman, with a history of tuberculous lymphadenitis treated in 2006, presented with a clinical scenario of inflammatory orbitopathy without loss of visual acuity progressing over 20 days. MRI showed a lesion centered on the soft tissues of the infero-lateral right orbit. A biopsy was performed, showing neuromuscular hamartoma on histology. The patient was put on a tapering dose of corticosteroids with clear clinical and anatomical improvement. Orbital CT follow-up was obtained two months after discontinuation of treatment, confirming the disappearance of the tumor mass. Hamartoma of the orbit is a very rare entity and may clinically simulate malignant neoplasms; the diagnosis is histologic. Given the difficulties encountered in the resection of these tumors, we believe that corticosteroids might be proposed as an alternative treatment that could modulate inflammation and bring about regression or disappearance of the tumor.

Ectomesenchymoma with Embryonal Rhabdomyosarcoma and Ganglioneuroma, Arising in Association with Benign Triton Tumor of the Tongue

Soft-tissue tumors known as "triton" tumors are rare lesions containing neural tissue and skeletal muscle at varying levels of maturity and malignant potential. Benign triton tumors, also called "neuromuscular choristomas" or "neuromuscular hamartomas," consist of neural tissue containing mature skeletal muscle in intimate relationship with peripheral nerve. These tumors are rare in the head and neck in children. Ectomesenchymomas are similar tumors consisting of a malignant mesenchymal component, usually embryonal rhabdomyosarcoma, and a neuroectodermal component represented by mature ganglion cells or primitive neuroblastic/neuroectodermal foci (primitive ectomesenchymoma). Benign triton tumors have been regarded as benign, whereas ectomesenchymomas have been operationally considered to be variants of rhabdomyosarcoma. We present here a unique case that combines features of these 2 entities in a recurrent lesion on the tongue of a 35-month-old girl. This lesion raises questions about the "benign" nature of benign triton tumor and its possible relationship to ectomesenchymoma.

Benign Triton Tumor: A Rare Entity in Head and Neck Region

Benign triton tumors (BTT) are very rare lesions composed of mature skeletal muscle and neural tissue. We report a case of a 14-year-old boy who presented with asymptomatic swelling of the chin over an 18-month duration which increased gradually to involve the left side of the lower lip. Clinically, a diagnosis of neurofibroma was made. Excisional biopsy confirmed the diagnosis of a BTT. Having an affinity for large nerve trunks like the brachial and sciatic, these tumors rarely occur in the head and neck region. When they do, they may involve the large central cranial nerve trunk and present as intracranial masses or involve the smaller peripheral nerve twigs and present as asymptomatic skin nodules, of which only four cases involving peripheral nerves are reported in the English literature. Here, we report the fifth documented case of a BTT involving the mental branch of the trigeminal nerve. A brief review of the literature is also provided.

Cutaneous neuromuscular choristoma: Case report and review of the literature

Neuromuscular choristoma, also known as benign triton tumor, is an uncommon developmental tumor composed of skeletal muscle and neural elements. The majority of cases reported have occurred in infants and have been generally associated with a large nerve, such as the brachial plexus or sciatic nerve. To date, only three cases of cutaneous lesions have been reported in the English literature. We describe a 28-year-old female presented with a soft, pedunculated papule on the presternal region since birth and review the literature of neuromuscular choristoma.

Benign Triton tumor of the tongue

A case of the extremely rare benign Triton tumor of the tongue is presented. This article presents new observations concerning associated hyperelastosis, the recognition of 2 distinct clinicopathological variants, and a new theory concerning pathogenesis that more closely fits current clinical and histopathological observations.

Cutaneous mesenchymal hamartoma with mixed myogenous differentiation

A 3-month-old infant girl presented with a polypoid lesion in the perianal region. No changes in this lesion had been noted since birth. Microscopic examination of the excised specimen showed a mixture of mesenchymal elements, dominated by haphazard thin fascicles of skeletal muscle. Collagen and vascular changes were also apparent. Immunohistochemistry showed positive staining for muscle-specific actin and desmin in the fascicular components of the lesion, and smooth muscle actin, desmin, and h-caldesmon positivity in a haphazard collection of muscle fibers in the deep dermis and anal submucosa. Numerous Verhoeff-van Gieson positive elastic fibers were also noted. Hamartomas containing skeletal muscle have rarely been reported outside of the head and neck region. They must be distinguished from a variety of other tumors, including juvenile rhabdomyoma, benign Triton tumor, and rhabdomyosarcoma.

Neuromuscular hamartoma in the mental region

J Oral Maxillofac Surg 61:397-400, 2003

Fetal rhabdomyoma of the head and neck: A clinicopathologic and immunophenotypic study of 24 cases

Twenty-four fetal rhabdomyomas (FRMs) of the head and neck occurring in 16 male and seven female patients (sex unknown in one), ranging from 3 days to 58 years of age (median, 4.5 years) are reported. Ten patients (42%) were ≤1 year old, six lesions (25%) were congenital, and 11 lesions (46%) occurred in patients ≥ 15 years of age. The median tumor size was 3.0 cm (range, 1.0 to 12.5 cm). The FRMs presented as well-defined, solitary masses arising within the soft tissue or mucosa (2:1) of the head and neck. The median follow-up in 15 cases was 48 months (range, 2 months to 52 years) after diagnosis. With the exception of one patient with a local recurrence, all patients were either alive and well or dead of unrelated causes. Eight cases, regarded as “classic” FRM, consisted predominantly of bland, primitive spindled cells associated with delicate, elongated skeletal muscle cells reminiscent of fetal myotubules that were haphazardly arranged in an abundant fibromyxoid stroma. The remaining 16 cases, designated as “intermediate” FRM, displayed both a greater degree and a greater number of cells with skeletal muscle differentiation as well as a variety of distinctive cytologic and architectural features. These included the presence of large, ganglion cell-like rhabdomyoblasts with vesicular nuclei and prominent nucleoli, interlacing ribbon or strap-like rhabdomyoblasts with deeply acidophilic cytoplasm, broad bundles of more delicate spindled rhabdomyoblasts arranged in fascicles simulating smooth muscle, an occasional plexiform pattern with infiltration of adipose tissue and skeletal muscle, focal intimate association with peripheral nerves, and rare areas of fibroblastic proliferation. Mitoses were not found in 19 of the 24 FRM cases, but in five tumors there were 1 to 14 mitoses/50 high-power fields. Marked nuclear atypia, anaplasia, and a “cambium layer” were uniformly absent. The FRMs typically stained for myoglobin, desmin, and muscle-specific actin with focal or rare staining for vimentin, smooth muscle actin, S-100 protein, glial fibrillary acidic protein, and Leu-7. Cytokeratin, epithelial membrane antigen, and CD68 antigen (with KP1) were not detected. This study expands on previous reports of FRM and demonstrates that it has both a broader age range and histologic spectrum than previously recognized. The mitotic rates of FRM as well as certain histologic features overlap with rhabdomyosarcoma; the lack of marked nuclear atypia is an important distinguishing feature. The intimate association of some FRMs with peripheral nerves and a focal fibroblastic proliferation in conjunction with S-100 protein and glial fibrillary acidic protein in some cases raises the possibility that at least some FRMs may be related to neuromuscular hamartoma (benign Triton tumor).