Hmm, maybe "Epidemic" by Lars von Trier? It's quite a weird movie, and a least a part of it is in a similar theme. Like Pathologic, it's pretty obscure too!
For something stylized European with great atmosphere (not very eastern or gothic, though) you could try "The City of Lost Children" and "Delicatessen" by Jean-Pierre Jeunet and Marc Caro.
Another film with amazing atmosphere (but not gothic either, rather a bit sci-fi), this time more Eastern European, see "Avalon" by Mamoru Oshii. At least the colour palette used in the movie should remind you of Pathologic a bit.
Nimród Amtal's "Kontroll" also has a great Eastern European atmosphere. Alas, it's not gothic either, rather very modern and gritty. Good, though, and worth trying!