Hydrothorax is a type of pleural effusion in which transudate accumulates in the pleural cavity. This condition is most likely to develop secondary to congestive heart failure, following an increase in hydrostatic pressure within the lungs. More rarely, hydrothorax can develop in 10% of patients with ascites which is called hepatic hydrothorax. It is often difficult to manage in end-stage liver failure and often fails to respond to therapy. Pleural effusions may also develop following the accumulation of other fluids within the pleural cavity; if the fluid is blood it is known as hemothorax (as in major chest injuries), if the fluid is pus it is known as pyothorax (resulting from chest infections), and if the fluid is lymph it is known as chylothorax (resulting from rupture of the thoracic duct). Treatment
Treatment of hydrothorax is difficult for several reasons. The underlying condition needs to be corrected; however, often the source of the hydrothorax is end stage liver disease and correctable only by transplant. Chest tube placement should not occur. Other measures such as a TIPS procedure are more effective as they treat the cause of the hydrothorax, but have complications such as worsened hepatic encephalopathy. See also
Pleural effusion
Pneumothorax

References

https://www.sciencedirect.com/topics/pharmacology-toxicology-and-pharmaceutical-science/hydrothorax
Garbuzenko D.V., Arefyev N.O. Hepatic hydrothorax: An update and review of the literature. World J. Hepatol. 2017; 9 (31): 1197-1204


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Mutations generally prevent the production of any functional VHL protein or result in a change of structure of VHL protein. This genetic disorder shows an autosomal dominant inheritance pattern, with about 20% of patients possessing a new mutation. There are usually several other tumors which are part of the syndrome, including tumors of the central nervous system, kidneys, pancreas, adrenal glands, epididymis, broad ligament, along with the endolymphatic sac. The vast majority of patients with an endolymphatic sac tumor have von Hippel-Lindau syndrome. Pathology findings
Tumors range from several millimeters up to 10 cm, with larger tumors more frequently seen in older patients. If the tumor is bilateral, it is almost always seen in a VHL patient. The tumor destroys the mastoid air spaces and extends into the middle ear and/or posterior cranial fossa. The microscopic appearance shows an unencapsulated, destructive growth, remodeling and invading bone. The tumor is arranged as simple, broad, non-complex papillary projections without large cystic spaces. The spaces are often fluid filled, have extravasated erythrocytes and/or inspissated material. The cells are cuboidal, usually single layered along the papillary structures, showing indistinct cell borders. The nuclei are round and hyperchromatic. Immunohistochemistry
The neoplastic cells are reactive with keratin, CK7, and Epithelial membrane antigen, but negative with TTF-1 and CK20. Cytogenetics
The germline mutations of VHL tumor suppressor gene will be found on 3p25-26 (short arm  of chromosome 3), usually between base pair 10,158,318 to 10,168,761. Differential diagnosis
The clinical and pathology differential are different.