The cytology and occurrence of granulocytomas in mussels

A non-neoplastic inflammatory cellular condition in the marine mussel Mytilus edulis is described and a possible relationship drawn between its incidence and water quality as effected by chronic insult by domestic and industrial waste products. This condition, termed a granulocytoma owing to its dominant constituent cell type, is capable of overcoming host encapsulation and inducing atrophy and autolysis of the digestive gland and may therefore represent a terminal condition.