Figure 1
Desmocollin-3 and TTF-1 immunoreactivities in a control case of squamous carcinoma of the lung (a–c), in various subtypes of large-cell lung carcinomas (d–o) and in sarcomatoid carcinoma (p–r). Neoplastic squamous cells are strongly positive for desmocollin-3 at the membrane level (b), whereas TTF-1 is negative in the same case (c). Basaloid variant of large-cell carcinoma (d) also expresses diffusely desmocollin-3 (e), in the absence of TTF-1 reactivity (f). Clear-cell variant of large-cell carcinoma (g, j) has a variable phenotypic profile, being some cases expressing desmocollin-3 but not TTF-1 (h, i), whereas others have the reverse profile, with mutually exclusive reactivity patterns (k, l). A large-cell carcinoma NOS having a marked lymphoid infiltration (m) expresses TTF-1 only, in the absence of desmocollin-3 reactivity (n, o). Finally a sarcomatoid carcinoma having predominant spindle-cell features (p) was completely negative for both markers (q, r). (First column to the left: hematoxylin and eosin, original magnification × 200; middle and right columns: immunoperoxidase for desmocollin-3 and TTF-1, respectively, original magnification × 200.)
