Suruya I cross posted some of this scenario with your cat on this other board and here is what one vet tech who specializes in emergency medicine for cats said: But your information you are leaving here is sketchy at best and if she knew the details that would help her to be able to help you: I knew that is sounded grave, I was hoping I was wrong.
Ok, could be any of the following:
Acute hepatic necrosis: caused by drug toxicity or other toxin, infectious disease, chemicals, hypoxia (oxygen pressure in blood).....need to immediately rule out potential drugs and toxins.....treatment includes IV fluids, antiemetics, meds for hepatoencephalopathy, and blood transfusion if coagulation disorders lead to grave condition. Need to treat agressively.
Hepatitis (granulomatous): caused by bacterial infection, viral, parasitic, protozoal of fungal disease (may want to rule out FIP)....needle aspiration, ultrasound-guided biopsy and/or culture on fluid/tissue drawn to differentiate......treatment includes IV fluids + potassium, antiemetics....but this is a multi-systemic disease so complications can develop and must treat those complications agressively.
Hepatic abcess: caused by bacteria, usually from the GI tract, or other infection of other organs........need to rule out pancreatic abcess, intestinal perforation, biliary tract obstruction, trauma or diabetes-related condition......ultrasound and/or US-guided biopsy to help confirm, +/- blood culturing........treatment includes IV fluids, agressive antibiotics, antiemetics....surgical removal and drainage may be necessary. Need to treat agressively.
Leptospirosis: caused by bacterial, contaminated water, contaminated urine of infected animals, infected meat, exposure to rodents, wildlife, livestock......need to consider ELISA, blood or urine culture.....needle biopsy also potential diagnostic......Treatment includes IV fluids, agressive antibiotics, possible diuretics.
Keep in mind these are very brief tips, not knowing the actual diagnosis, current treatment approach, diagnostics approached, etc. In all diseases mentioned, agressive care is imperative, and most likely, an ultrasound and/or guided biopsy is going to be needed to confirm. (unless the vet already obtained an abdominocentisis and did a cytology on it or blood culture). Also, all the conditions can carry complications, so, with severe necrosis, coagulation disorders, septicemia, these can complicate the matter and prohibit worsening problems. Don't want to give false hope here, with the exception of abcess, these can be poor prognoses. Agressive treatment may help regenerate the liver, but need to find the underlying cause in order to treat the most effective.
The poster said kitty had swallowed something, was it a drug, pill or ? Also, where was the lump located, abdominally or elsewhere?
Of course, like you, not knowing the level of care, would advise to find the most experienced vet in the area, even a consult if necessary....time is going to be of the essense here, very agressive treatment approach!!