An intepretation of the structural changes responsible for the chronicity of rhinoscleroma

Objective: To identify the structural changes of the proliferative phase of rhinoscleroma which could be responsible for the chronicity of the disease , Study Design: Observational research. Methods: Samples of friable tissue taken from the nasal mucosa of nine untreated patients were processed for l ight and ultrastructural microscopy, Results: The majority of changes contr ibuting to the chronicity of the disease occurred in the subepithelium and followed three closely related but distinct events. In the first (infiltrat ive), subepithelial invasion by the Klebsiella was followed by its active m ultiplication and proliferation of capillaries, In the second (neutrophilic ), large numbers of neutrophils were delivered into this space. Neutrophils actively phagocytized the Klebsiella but appeared to die at an accelerated rate without completing digestion of the microorganisms, In the third even t: (histiocytic), histiocytes entered the subepithelium and engaged in unre strained phagocytosis of decaying neutrophils, Klebsiella, and debris. Duri ng this process, the histiocytes' phagosomes underwent massive dilation, th us becoming Mikulicz cells. Mikulicz cells were unable to consistently dest roy the Klebsiella and eventually ruptured, releasing them into the interst itium. Evidence was found that an autophagic process might contribute to ph agosome distention and to the rupture of the vacuolar membranes and cell wa ll. Conclusions: Several critical changes responsible for the chronicity of rhinoscleroma occur during the proliferative phase of the disease, The ma jority of these take place in the subepithelium and include: 1) factors lea ding to the transformation of histiocytes into Mikulicz cells, 2) the inabi lity of these cells to consistently destroy the Kebsiella, 3) their rupture releasing viable Klebsiella, and 4) the intrinsic resistance of the pathog en.