A pinkish or red color may be present due to abrasion or hemorrhage. The disease has also been found to infect internal organs although this is quite rare. Lymphocystis is caused by a virus which is released into the water when growths on an infected fish rupture. The virus can infect healthy walleye by entering skin abrasions or cuts and then attacking cells in the connective tissue. Eventually these growths will rupture, releasing more virus particles into the water, and the lesions will become scarred over.
Various authors differ on the incubation period of lymphocystis.
Some report that a fish infected in the spring will develop growths the following spring. Others indicate that incubation may take only a few weeks. Temperature may be an important factor in determining this period. Dermal sarcoma may be less seasonal than lymphocystis but since the two diseases are often confused its frequency of occurrence is not yet known. A 1976 Canadian study examined 50 tumors which were thought to be lymphocystis and found twice as many dermal sarcomas as lymphocystis tumors.