Lung epithelial stem cells and their niches : Fgf10 takes center stage

Throughout life adult animals crucially depend on stem cell populations to maintain and repair their tissues to ensure life-long organ function. Stem cells are characterized by their capacity to extensively self-renew and give rise to one or more differentiated cell types. These powerful stem cell properties are key to meet the changing demand for tissue replacement during normal lung homeostasis and regeneration after lung injury. Great strides have been made over the last few years to identify and characterize lung epithelial stem cells as well as their lineage relationships. Unfortunately, knowledge on what regulates the behavior and fate specification of lung epithelial stem cells is still limited, but involves communication with their microenvironment or niche, a local tissue environment that hosts and influences the behaviors or characteristics of stem cells and that comprises other cell types and extracellular matrix. As such, an intimate and dynamic epithelial-mesenchymal cross-talk, which is also essential during lung development, is required for normal homeostasis and to mount an appropriate regenerative response after lung injury. Fibroblast growth factor 10 (Fgf10) signaling in particular seems to be a well-conserved signaling pathway governing epithelial-mesenchymal interactions during lung development as well as between different adult lung epithelial stem cells and their niches. On the other hand, disruption of these reciprocal interactions leads to a dysfunctional epithelial stem cell-niche unit, which may culminate in chronic lung diseases such as chronic obstructive pulmonary disease (COPD), chronic asthma and idiopathic pulmonary fibrosis (IPF)

Giant retroperitoneal lipoma: a case report Lipoma gigante do retroperitônio: relato de caso

BACKGROUND: Retroperitoneal lipoma is an extremely rare neoplasm. AIMS: The authors report a case of giant retroperitoneal lipoma in a 32-year-old white female, with a history of pain and an abdominal mass over a 2-year period. Total abdominal ultrasonography and barium enema showed a large mass located in the retroperitoneal space behind the ascending colon. Laparotomy showed a large encapsulated tumor measuring 20 x 13 x 10 cm and weighing 3.400 g. The histological study revealed a benign neoplasm of fatty cells. CONCLUSION: The patient remains well 17 years after surgery, without recurrentce of the disease.<br>RACIONAL: O lipoma é a neoplasia mesenquimal mais freqüente, raramente localizada no retroperitônio. Na maioria das vezes, o diagnóstico diferencial pré-operatório com os lipossarcomas de baixo grau de malignidade é difícil de ser estabelecido. OBJETIVO: Apresentar um caso de lipoma gigante retroperitoneal em mulher de 32 anos que há 2 anos apresentava história de dor e tumor abdominal palpável. A ultra-sonografia abdominal e o enema opaco mostraram grande massa localizada no retroperitônio, que deslocava o ceco e o cólon ascendente. A laparotomia mostrou tumor encapsulado com 20 x 13 x 10 cm e 3.400 g de peso. O estudo histopatológico mostrou presença de lipoma retroperitonial. A paciente encontra-se bem, sem recidiva da doença, 17 anos após a cirurgia