Tuberous sclerosis: clinicopathologic features and review of the literature

Oral and skin manifestations of tuberous sclerosis complex

Tuberous sclerosis complex is a genetic disease characterized by multisystemic hamartomas with variable and non-specific clinical manifestations. The disease is associated with mutations of genes encoding the proteins hamartin and tuberin. The hamartin/tuberin complex plays an anti-tumor function by inhibiting mammalian target of rapamycin. The diagnostic criteria for the disease were reviewed at a consensus conference in 2012. Evidence of mutations of tuberous sclerosis complex 1 or 2 genes has become a clinical and independent diagnostic criterion. Among the clinical criteria used, two oral criteria include the presence of three or more enamel pits and the presence of two or more oral fibromas. Several dermatological criteria are included within these criteria and are of interest in our specialty when these are localized at the cephalic extremity.

Clinicopathological investigation of odontogenic fibroma in tuberous sclerosis complex

Tuberous sclerosis complex (TSC) is an autosomal dominant inherited disease characterized by systemic hamartoma and diverse systemic features. TSC1 and TSC2 are the causative genes, and mental retardation, epileptic seizures, and facial angiofibroma develop in many patients with the disease. The case of a patient with TSC who developed a central odontogenic fibroma of the mandible is reported here. The patient was a 21-year-old woman who was referred with a swelling of the labial gingiva in the region of the right lower lateral incisor and canine. Dental radiography revealed a multilocular radiolucent region with a clear boundary. The right lower lateral incisor and canine were continuous with the lesion and thus were excised en bloc. The lesion was encapsulated and easily dissected. The diagnosis on immunohistological staining was odontogenic fibroma without an epithelial component. TSC1/2 gene mutation causes abnormal activation of mammalian target of rapamycin (mTOR) downstream of the PI3K-AKT pathway. The odontogenic fibroma in this patient was positive for mTOR, suggesting that the development of the odontogenic fibroma was the result of abnormal activation of mTOR, as in angiofibroma. The clinical course of this patient is presented and the developmental mechanism of central odontogenic fibroma is discussed.

The impact of mosaicism in preimplantation genetic diagnosis (PGD): approaches to PGD for dominant disorders in couples without family history

OBJECTIVES

Mosaicism in certain dominant disorders may result in a 'non-Mendelian' transmission for the causative mutation. Preimplantation genetic diagnosis (PGD) is available for patients with inherited disorders to achieve an unaffected pregnancy. We present our experience for two female patients with different dominantly inherited autosomal disorders; neurofibromatosis type 1 (NF1) and tuberous sclerosis complex type 2 (TSC2).

METHODS

PGD protocol development was carried out using single cells from the patients. PGD was carried out on polar bodies and different embryonic cells.

RESULTS

Protocol development for NF1 using lymphocytes from the patient suggested mosaicism for the mutation. This was supported further by quantitative fluorescent-PCR performed on genomic DNA. During PGD, polar bodies and blastomeres lacked the mutation that probably was absent or present at very low levels in the patient's germline. Single lymphocyte analysis during protocol development for TSC2 did not indicate mosaicism; however, analysis of single buccal cells and multiple embryo biopsies across two consecutive IVF/PGD cycles confirmed gonosomal mosaicism.

CONCLUSIONS

The trend in PGD is for blastocyst biopsy followed by whole genome amplification, eliminating single cell analysis. In the case of certain dominantly inherited disorders, pre-PGD single cell analysis is beneficial to identify potential mosaicism that ensures robust protocols. © 2016 John Wiley & Sons, Ltd.

Tuberous sclerosis with oral manifestations: A rare case report

Tuberous sclerosis complex (TSC) is a neurocutaneous syndrome, inherited as an autosomal dominant trait with a high incidence of sporadic cases and protean clinical expression, with a incidence of prevalence between 1 in 10,000 and 1 in 170,000. The cardinal features of TSC are skin lesions, convulsive seizures, and mental retardation. We report a sporadically occurring case of definite TSC in a young female who presented with oral and cutaneous manifestations without mental retardation or history of convulsive seizures, which to the best of our knowledge has not been reported so far.

mTORC1 Prevents Preosteoblast Differentiation through the Notch Signaling Pathway

The mechanistic target of rapamycin (mTOR) integrates both intracellular and extracellular signals to regulate cell growth and metabolism. However, the role of mTOR signaling in osteoblast differentiation and bone formation is undefined, and the underlying mechanisms have not been elucidated. Here, we report that activation of mTOR complex 1 (mTORC1) is required for preosteoblast proliferation; however, inactivation of mTORC1 is essential for their differentiation and maturation. Inhibition of mTORC1 prevented preosteoblast proliferation, but enhanced their differentiation in vitro and in mice. Activation of mTORC1 by deletion of tuberous sclerosis 1 (Tsc1) in preosteoblasts produced immature woven bone in mice due to excess proliferation but impaired differentiation and maturation of the cells. The mTORC1-specific inhibitor, rapamycin, restored these in vitro and in vivo phenotypic changes. Mechanistically, mTORC1 prevented osteoblast maturation through activation of the STAT3/p63/Jagged/Notch pathway and downregulation of Runx2. Preosteoblasts with hyperactive mTORC1 reacquired the capacity to fully differentiate and maturate when subjected to inhibition of the Notch pathway. Together, these findings identified the role of mTORC1 in osteoblast formation and established that mTORC1 prevents preosteoblast differentiation and maturation through activation of the Notch pathway.

The coordinated activities of osteoblasts and osteoclasts in bone deposition and resorption form the internal structure of bone. Disruption of the balance between bone formation and resorption results in loss of bone mass and causes bone diseases such as osteoporosis. Current therapies for osteoporosis are limited to anti-resorptive agents, while bone diseases due to reduced osteoblast activity, such as senile osteoporosis, urgently require targeted treatment and novel strategies to promote bone formation. mTORC1 has emerged as a critical regulator of bone formation and is therefore a potential target in the development of novel bone-promoting therapeutics. Identifying the detailed function of mTORC1 in bone formation and clarifying the underlying mechanisms may uncover useful therapeutic targets. In this study, we reveal the role of mTORC1 in osteoblast formation. mTORC1 stimulated preosteoblast proliferation but prevented their differentiation and attenuated bone formation via activation of the Notch pathway. Pharmaceutical coordination of the pathways and agents in preosteoblasts may be beneficial in bone formation.

Scalp fibroma: a rare cutaneous manifestation of tuberous sclerosis

We report a case of a 23-year-old woman with a history of generalised tonic-clonic seizures, reddish brown maculopapular swelling over the face and an enlarging swelling over the scalp. Physical examinations revealed angiofibroma of the face and other typical cutaneous lesions of tuberous sclerosis, for example, shagreen patch and periungual fibroma. Scalp swelling was labelled as fibroma by dermatologists, which was further supported by the histopathological findings. Fibroma of the face is one of the commonest lesions, however, fibroma of the scalp is a rarely described entity.

Tuberous sclerosis: a case report

Tuberous sclerosis is an inherited neurocutaneous disorder that occurs in approximately 1 in 7,500 live births. It is characterized by benign neoplasms of the skin, heart, kidneys, lungs, central nervous system, and mucosa. Oral lesions are usually fibrous in nature and most commonly occur on the anterior gingivae. Patients may suffer with epilepsy and learning difficulties, which may complicate dental management. When a 10-year-old girl with a history of tuberous sclerosis was brought in for a routine dental check-up, a leafy growth on the anterior gingiva was detected. An excisional biopsy was carried out. Histologically, the appearance was described as nonspecific, but was consistent with a diagnosis of tuberous sclerosis. Tuberous sclerosis is a rare condition that may exhibit oral manifestations. The patients may also exhibit epilepsy and learning difficulties. Dental management of affected patients may therefore be more complicated and complex.

Malignant fibrous histiocytoma (undifferentiated high-grade pleomorphic sarcoma) occurring in tuberous sclerosis: a case report

Tuberous sclerosis is an autosomal dominant genetic disorder that is characterized by the early development of hamartomas, malformations, and congenital tumors of the nervous system, skin, kidneys, lungs, and heart. Variable clinical expressivity has been reported and more than one gene can be responsible for the disorder. Benign neoplasias accompanying the syndrome are common but malignant neoplasias are rare, being generally mesenchymal and possibly affecting the jaws. We report here a clinical case of a malignant fibrous histiocytoma (undifferentiated high-grade pleomorphic sarcoma) of the mandible in a patient with tuberous sclerosis.

Tuberous sclerosis complex: a review

Tuberous sclerosis complex (TSC) is an inherited neurocutaneous disorder characterized by the potential for hamartoma formation in almost every organ. The inheritance is autosomal dominant with almost complete penetrance but variable expressivity. The two gene loci that code for TSC are TSC1, located on chromosome 9q34, and TSC2 on 16p13.3. TSC complex may affect the skin, central nervous system, kidneys, heart, eyes, blood vessels, lungs, bone, and gastrointestinal tract. The diagnosis of TSC is based on the identification of hamartomas in more than one organ system. Treatment should be symptomatic and organ specific. A multidisciplinary management approach is necessary.

Fibrolipomatous hamartoma in a patient with tuberous sclerosis: Report of a case

Tuberous sclerosis is a rare congenital disorder with an incidence of 1 in 6000 births. The classic triad is seizure, mental deficiency, and angiofibromas. Orofacial manifestations include fibrous hyperplasia, hemangioma, bifid uvula, cleft lip and palate, macroglossia, high arched palate, and enamel defects. Benign tumors of the jaws including desmoplastic fibroma, calcifying odontogenic tumor, and odontogenic myxoma have been recently reported in tuberous sclerosis. This case report adds fibrolipomatous hamartoma of the mandible to this list.