Resolution of multifocal micronodular pneumocyte hyperplasia with everolimus in a patient with tuberous sclerosis complex

A Gain-of-Function Mutation in Mechanistic Target of Rapamycin Results in a Tuberous Sclerosis Complex-Like Manifestation of Parenchymal Lung Disease

Dysregulation of the mechanistic target of rapamycin (mTOR) signaling pathway rarely results in parenchymal lung disease, prototypically multifocal multinodular pneumocyte hyperplasia (MMPH) and lymphangioleiomyomatosis (LAM). Although LAM can occur sporadically, to our knowledge, MMPH has not previously been described independent of tuberous sclerosis complex (TSC), a syndrome caused by germline mutations in the tumor suppressor genes TSC1 or TSC2. We report the case of a man with a history of multiple malignancies who presented with incidental chest imaging findings of innumerable ground-glass nodules and several air-filled cysts, offering a diagnostic challenge. Histopathologic findings on lung biopsy identified nodular foci of pneumocyte hyperplasia with negative Human Melanoma Black-45 staining. Next-generation DNA sequencing of the tissue showed a previously described gain-of-function mutation in MTOR. We propose that this patient's TSC-like pulmonary disease is a direct result of this mutation, a novel finding that underscores the role of Next-generation DNA sequencing in cryptic histopathology.

Tuberous Sclerosis Due to Deletion of Exons 4-8 in TSC2 Gene, Favourably Responding to Phenytoin and Everolimus: A Case Report

A case of tuberous sclerosis (TSC) caused by a previously unreported mutation, with epilepsy responding well to phenytoin (PHT) and multilocular benign tumors regressing with everolimus, has not been documented before, to the best of our knowledge. The patient is a 24-year-old female who was diagnosed with tuberous sclerosis complex (TSC) at the age of seven due to epilepsy and the presence of multiple hamartomas, including angiofibromas, angiomyolipomas, lymphangioleiomyomas, rhabdomyomas, and astrocytomas, throughout her body. She also has a history of developmental delay, mild cognitive impairment, adjustment disorder, claustrophobia, recurrent depressive episodes, anxiety disorder, and autism spectrum disorder. Genetic testing confirmed a deletion of exons 4-8 in the TSC2 gene. At the age of 10, monotherapy with PHT was started, which had such a favorable effect that no more seizures occurred until the age of 19. From the age of 19, she also received everolimus, as a result of which the multi-organ hamartomas regressed significantly. This case shows that epilepsy in TSC is not intractable, that phenytoin could be an option for epilepsy in TSC patients, and that everolimus is very effective in terms of regression of benign tumors.

Genotype and Phenotype Landscape of 283 Japanese Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by multiple dysplastic organ lesions and neuropsychiatric symptoms, caused by loss of function mutations in either TSC1 or TSC2. Genotype and phenotype analyses are conducted worldwide, but there have been few large-scale studies on Japanese patients, and there are still many unclear points. This study analyzed 283 Japanese patients with TSC (225 definite, 53 possible, and 5 genetic diagnoses). A total of 200 mutations (64 TSC1, 136 TSC2) were identified, of which 17 were mosaic mutations, 11 were large intragenic deletions, and four were splicing abnormalities due to deep intronic mutations. Several lesions and symptoms differed in prevalence and severity between TSC1 and TSC2 patients and were generally more severe in TSC2 patients. Moreover, TSC2 missense and in-frame mutations may attenuate skin and renal symptoms compared to other TSC2 mutations. Genetic testing revealed that approximately 20% of parents of a proband had mild TSC, which could have been missed. The patient demographics presented in this study revealed a high frequency of TSC1 patients and a low prevalence of epilepsy compared to global statistics. More patients with mild neuropsychiatric phenotypes were diagnosed in Japan, seemingly due to a higher utilization of brain imaging, and suggesting the possibility that a significant amount of mild TSC patients may not be correctly diagnosed worldwide.