Rare Lung Manifestation of Multifocal Micronodular Pneumocyte Hyperplasia in a Teenage Girl with Tuberous Sclerosis Complex

Tuberous sclerosis complex (TSC) is a hereditary neurocutaneous syndrome with a classic triad of seizures, mental retardation, and adenoma sebaceum. It is inherited by an autosomal dominant pattern and is caused by a mutation in the TSC1 and TSC2 genes encoding hamartin and tuberin respectively, both of which are thought to act as tumor suppressor genes (1). Lack of functional hamartin or tuberin may explain the development of hamartomas and various tumors in TSC. Almost all systems or organs of the body can be involved in TSC. Clinical manifestations are unique in many cases but in some cases, characteristic findings from imaging are the first step to raise a possibility of TSC. Hamartomas in TSC patients are most commonly found in the skin, kidneys, brain, and heart. Less frequently, they can involve the retina, gingiva, bones, gastrointestinal tract, and lungs. Lymphangioleiomyomatosis (LAM) is a well known and major feature of the pulmonary manifestation of TSC. Pulmonary manifestations are known to occur in approximately 1–2.3% of TSC patients, but the incidence turned out to be higher based on radiologic findings in up to 26–39% of female TSC patients (2). More recently, multifocal micronodular pneumocyte hyperplasia (MMPH) has been reported to occur in association with TSC (3, 4). MMPH is a hamartomatous process of the lung with multiple small nodules which are composed of type II pneumocytes. MMPH is not a new entity, but if it is an initial presentation of TSC and we are not familiar with this rare manifestation of TSC, it may lead incorrectly to other diagnoses such as miliary tuberculosis or metastatic lung disease. MMPH in TSC has been rarely reported in children or adolescents (5). Here, we report a teenage girl with MMPH and TSC which mimicked miliary tuberculosis at the initial presentation. Rare Lung Manifestation of Multifocal Micronodular Pneumocyte Hyperplasia in a Teenage Girl with Tuberous Sclerosis Complex :