[Side-effects of treatment on the structure of the lung]

The morphology of therapy-associated changes in the lungs is determined by largely unspecific findings, since various toxic injuries lead to a formal-pathogenetically almost identical reaction pattern. In addition to direct toxic injuries, the morphological investigation also reveals evidence of allergic and individual-specific complex reaction patterns. In an early phase (Phase I), pathological-anatomical degenerative changes affecting the endothelial and epithelial cells, basal membrane, mesenchymal and matrix structures--initially functionally partially reversible, but then extending to complete necroses--can be found. Measurable functional disorders are demonstrated in particular by disturbed permeability of the capillaries, increased interstitial fluid, and functional disorders of the pneumocytes (shortage of surfactant, defective intercellular connections). The cellular exsudative phase (Phase II) is characterised by an accumulation and stimulation of macrophages, a variably pronounced immunological infiltration with and without eosinophilia, and regenerative findings affecting membrane structures, endothelial and epithelial cells. The fibrotic, chronic phase (Phase III) leads to largely irreparable, predominantly interstitial, fibrosis in the region of the non-fibrillar matrix, and to an increased production of collagenous fibres, elastic fibres and muscle fibres by myofibroblasts in an interaction with macrophages. Atypical proliferations of pneumocyts, pronounced eosinophilia, predominantly endangiitic vascular changes, etc. may, to some extent, indicate injuries by certain groups of substances or ionising radiation. Heterogeneous, multi-focal toxic pulmonary changes, that permit only limited interpretation in biopsy material, together with the possibilities of prior lung diseases in the elderly patients require caution on the part of the pathologist when it comes to a causal-pathogenetic interpretation of formal-pathogenetically unequivocally establishable findings.