A patient was diagnosed with caseating necrotic by a pulmonologist. Usually, the

A patient was diagnosed with caseating necrotic by a pulmonologist. Usually, the patients have tuberculosis, but in this case, the doctor diagnosed this patient with syphilis instead. So the question is, How is the pneumonia diagnosed? Does the doctor take the tissue and submit it to histology? Is it a histology stain that is done? How would the doctor see the spiral-shaped bacteria? How is it diagnosed? I also need a credible source, not Wikipedia. Let me know if you can help?