Primary signet-ring cell carcinoma of the lung: Histochemical and immunohistochemical characterization

To establish criteria for differential diagnosis and to clarify the histoge nesis of primary signet-ring cell carcinoma (SRCC) of the lung, five cases were studied by mucin-histochemical and immunohistochemical analyses and co mpared with SRCC of the gastrointestinal tract and mucus-producing adenocar cinoma of the lung. The proportion of signet-ring cell component varied fro m 10% to 90% in four cases, and the remaining tumor was a pure SRCC. Mucin- histochemistry showed a close similarity between lung SRCC and goblet cell- type or bronchial gland cell-type adenocarcinoma of the lung. Eighty percen t of SRCCs showed positive immunoreactions for lactoferrin, a marker of bro nchial gland cell differentiation, the results: being consistent with the c onclusions in previous studies that lung SRCC is closely related to bronchi al gland cell-type adenocarcinoma. The incidence of Ii-uas mutation detecte d by the restriction fragment length polymorphism method was relatively hig h in lung SRCC (three of five) and goblet cell-type adenocarcinoma of the l ung (four of four). Mucin-histochemistry indicated that lung SRCC has mucin production similar to that of the colon and colorectal-type SRCCs of the s tomach but not to that of gastroduodenal-type SRCC of the stomach. Immunohi stochemical staining for MUC-1 and MUC-2 glycoproteins showed a distinct di fference; lung SRCC was positive for MUC-1 but negative for MUC-2, whereas colon SRCC and colorectal-type gastric SRCC were negative for MUC1 but posi tive for MUC-2. Thus, by a combination of mucin-histochemistry and MUG-I an d MUC-2 immunohistochemistry, primary lung SRCC can be distinguished from m etastatic lung SRCC originating in the gastrointestinal tract. Copyright (C ) 1999 by W.B. Saunders Company.