Exclusion of Primary Mediastinal Neoplastic Lesions in Differential Diagnosis Against Mediastinal Metastases of Primary Lung Cancers

Primary lung cancers can be very small and are primarily not detected by the diagnostic methods described.

The primaries can be masked when cancer-related bronchial stenosis has resulted in retention pneumonia. In such cases, often with small primaries, large mediastinal lymph node metastases may have developed. These can mimic primary mediastinal neoplasms. Therefore, in biopsy specimens obtained by mediastinoscopy, primary me-diastinal cancers must be ruled out or definitely confirmed by histopathological investigations.

The most important primary mediastinal cancers are:

1) Hodgkin's disease

2) Lymphomas

3) Thymomas

These are illustrated in Figs. 18 and 19.

Fig. 7. Combined histo- and cytopatho-logical techniques applied to ensure lung cancer diagnosis. a Endoscopic biopsy techniques plus exfoliative cytology. b Transthoracic aspiration cytology (FNAC). c Transcarinal puncture of bifurcation lymph node(s) in advanced cases. Diagnoses made by investigations including typing by histopathology only in biopsies were secure in 84% of cases, whereas when all histo- and cytopatho-logical techniques are used the diagnoses are secure in 96%

Fig. 7. Combined histo- and cytopatho-logical techniques applied to ensure lung cancer diagnosis. a Endoscopic biopsy techniques plus exfoliative cytology. b Transthoracic aspiration cytology (FNAC). c Transcarinal puncture of bifurcation lymph node(s) in advanced cases. Diagnoses made by investigations including typing by histopathology only in biopsies were secure in 84% of cases, whereas when all histo- and cytopatho-logical techniques are used the diagnoses are secure in 96%

Figs. 8-10. Diagnosis of small cell lung cancers (SCLCs) in primaries and lymph node metastasis

Fig. 8. SCLC: small cancer cell cluster with spindle-shaped nuclei and sparse cytoplasm. In MiB I reaction, in most cases 70-80% of the nuclei are stained, but mitoses hardly detectable

Fig. 9. SCLC: strongly positive cytoplas-mic reaction with antibodies directed to cytokeratins

Fig. 10. SCLC: FNAC of a suspect lymph node. The very small cancer cell clusters with partly spindle-shaped and partly round nuclei together with cyto-keratin positivity allow the diagnosis of SCLC. Ultrarapid immunohistochemical reaction can be performed intraopera-tively for an immediate decision on operability

Fig. 10. SCLC: FNAC of a suspect lymph node. The very small cancer cell clusters with partly spindle-shaped and partly round nuclei together with cyto-keratin positivity allow the diagnosis of SCLC. Ultrarapid immunohistochemical reaction can be performed intraopera-tively for an immediate decision on operability

Figs. 11-14. Diagnosis of adenocarcino-mas with exclusion of carcinoids in FNAC smears

Fig. 11. Adenocarcinomas of the lung (non-small-cell lung cancer; NSCLC): highly differentiated adenocarcinoma with moderately polymorphous nuclei located eccentrically in the cytoplasm. A carcinoid character of the lesion must be ruled out using antibodies directed to chromogranin, synaptophy-sin, etc. The antibody MiB I should be used for determination of proliferative activity. SLN search can give a reliable indication of whether or not lesion is operable

Fig. 12. Cytology of moderately differentiated adenocarcinoma (NSCLC). SLN search and intraoperative staging help to clear the question of operability

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