Dropsy
In the case of 'dropsy' or 'pine-cone disease' the fish's body often swells up, the eyes may start to bulge out (exophthalmia) and some or all of the scales may stand out from the body, giving the appearance of a pine-cone, hence the common name. This is an extremely serious condition having many possible causes. It is important to understand that it is merely a clinical description of the condition: there is no actual disease called ‘dropsy'. Dropsy could indicate a contagious infection so it makes sense to isolate any affected fish.
A long-term bath of salt at one-ounce per gallon may help reduce osmotic stress and in general I would recommend a course of antibiotics in case the problem is bacterial. It is reasonable to assume that the condition is stressful to fish and, unless there are signs of improvement, it may be kinder to euthanase the fish, rather than prolong its suffering.