I have a recollection of reading this particular horror story as a young teen (circa 1993?), but cannot now find it. It was written in a style reminiscent of Edgar Allan Poe’s. (I have browsed the latter’s tales to no avail, however.) Here follows the story as I remember it. Thanks in advance to anyone who can point me in the right direction.
(The setting might be the 19th century.) A man travels (possibly to India or South America) to meet a friend (probably an archaeologist or explorer) who wrote to ask him to come since he has fallen terribly ill. There, the main character finds his friend uncooperative and secretive. The sick man’s health fluctuates, and his bouts of illness correlate with large lumps appearing on his skin.
One night, the puzzled protagonist decides to spy on his friend, and sees him cutting open one of his cysts with a knife. An imp-like creature emerges from the wound and addresses the feverish man. I do not remember its exact words; they seemed to imply that the infected fellow had a duty to perform should he wish to be rid of this curse. It left me with the general impression that he had to return an artifact or restore something to its earlier condition, but that this task was impossible, dooming him to a (hopefully short) life of torment borne of his own flesh.
I believe the story ends at this point, or maybe shortly afterwards as the onlooking character reels in horror and flees.