It is proposed a medical knowledge representation of inflammatory protein variations involving complex relationships, frequently encountered in Internal Medicine. A linguistic model has been represented by a fuzzy set pattern expressing relative variations of serum proteins levels. Weights have been introduced into this pattern to translate relative importance among proteins. Three indexes or measures (possibility, necessity and truth-possibility) have been used for pattern matching purposes. Finally, a separating power yielding non fuzzy partitions has allowed to assign the corresponding diagnoses to patients (over 160 cases).