Complementary value of electron microscopy and immunohistochemistry in the diagnosis of non-small cell lung cancer: A potential role for electron microscopy in the era of targeted therapy.

With the identification of therapeutic targets for lung adenocarcinoma, it has become mandatory to distinguish it from other entities. Some cases remain classified as non-small cell lung carcinoma, not otherwise specified (NSCLC-NOS) with immunohistochemistry. Electron microscopy (EM) can be useful, allowing the identification of glandular differentiation. The aim of this study was to determine the complementary value of immunohistochemistry and EM.Forty-eight NSCLC-NOS cases were selected (PSMAR-Biobank, Barcelona, Spain). Immunohistochemistry (TTF-1, p40) was performed. Tissue was retrieved from paraffin blocks. Results were compared to the final diagnosis, derived from combination of light microscopy, immunohistochemistry, EM, molecular studies and resection specimen.Immunohistochemistry concurred with final diagnosis in 36 cases (75%, Kappa = 0.517). EM agreed with final diagnosis in 35 (72.9%, Kappa = 0.471). Immunohistochemistry had a sensitivity = 73%, specificity = 100%, positive predictive value (PPV) = 100% and negative predictive value (NPV) = 52.4% for adenocarcinoma. All adenocarcinoma cases not solved by immunohistochemistry (n = 10) were classified by EM, and vice versa. Data from EM were identical to those of immunohistochemistry: sensitivity = 73%, specificity = 100%, PPV = 100% and NPV = 52.4%. Combining both techniques, 47 cases were coincident with final diagnosis (97.9%, Kappa = 0.943).EM can provide valuable information in subtyping NSCLC-NOS, being particularly useful when immunohistochemistry is inconclusive. EM could be considered as a complementary tool for decision-making in NSCLC-NOS.

Neumonía organizada asociada a tratamiento con trastuzumab / Organizing Pneumonia Associated with the Use of Trastuzumab

La neumonía organizada es una entidad clinicohistológica que suele manifestarse de forma subaguda con clínica respiratoria e infiltrados pulmonares. Puede ser de causa desconocida (criptogenética) o estar asociada a distintas enfermedades, infecciones o fármacos. Presentamos el caso de una paciente de 60 años con antecedentes de una neoplasia de mama, motivo por el cual seguía tratamiento con trastuzumab, un anticuerpo monoclonal anti-HER2, a quien se detectó de forma casual un infiltrado pulmonar, cuya biopsia transbronquial fue diagnóstica de neumonía organizada. Tras la retirada del fármaco desapareció el infiltrado pulmonar. Debido a la creciente utilización de la terapia biológica en diferentes campos de la clínica, nos parece de interés comunicar esta forma de afectación pulmonar atribuible al anticuerpo monoclonal trastuzumab(AU)

Organizing pneumonia is a clinical and histological condition in which the onset is usually subacute with respiratory symptoms and pulmonary infiltrates. It may be unknown origin (cryptogenic) or associated with other illnesses, infectious diseases or drugs. We present a 60 year-old female patient with a previous history of breast cancer, who was being treated with trastuzumab, an antiHER2 monoclonal antibody. She was diagnosed with casual pulmonary infiltrates that had histological changes compatible with organizing pneumonia. The pulmonary infiltrates disappeared on withdrawing trastuzumab treatment. Due to the increasing use of biological therapies in different medical areas, we believe it is of interest to report this pulmonary involvement attributed to the monoclonal antibody trastuzumab(AU)