The paper describes the Diagnostic Panel Software System designed for the "spinal deformity and degenerative diseases of the spine" subject domain. The work is based on the methods of statistical processing of the data obtained from medical documents written in a natural language. The software system based on patient's clinical and laboratory test results helps physicians determine a preliminary diagnosis of the patient and get quick information on the necessity of certain measures for final diagnosis and selection of the optimal treatment strategy. The Diagnostic Panel Software System uses case-based approach for the representation of knowledge extracted from a variety of natural language texts. Developed case-based approach is based on model-theoretic methods of subject domain ontology formalization. For the processing of knowledge represented in system the formal concept analysis methodology is used.