From Cancer Mimicking Orphan Lung Disease to Orphan Thoracic Oncology

International audienceA variety of rare neoplastic and non-neoplastic disorders may develop in the lung, the pleura, and the mediastinum. Some may have a propensity to mimic lung carcinoma as well as benign orphan lung diseases at some level of examination, as they may share with these clinical, imaging, pathological, and even molecular features. Challenges in the differential diagnoses among reciprocal mimics are well illustrated through examples as bronchioloalveolar carcinoma, primary pulmonary lymphomas, and vascular sarcomas. Pseudotumors have further been described, actually corresponding to a heterogeneous group of diseases characterised by circumscribed fibrous tissue and inflammatory cells. Among the inflammatory pseudotumors, neoplastic/non-neoplastic borderline disorders have been identified, such as inflammatory myofibroblastic tumor, which presents with clonal proliferation and has eventually emerged as a true neoplasm. Finally, some rare pulmonary diseases are emerging as borderline neoplastic non-neoplastic disorders, that require multidisciplinary expertise both in the field of orphan pulmonary diseases and in thoracic oncology, including amyloidosis or even Langerhans cell histiocytosis. Ultimately, implementing multi-disciplinary expert consensus is mandatory to determine the optimal management of these disorders

Histopathologic Diagnosis of Fungal Infections in the 21st Century

Summary: Fungal infections are becoming more frequent because of expansion of at-risk populations and the use of treatment modalities that permit longer survival of these patients. Because histopathologic examination of tissues detects fungal invasion of tissues and vessels as well as the host reaction to the fungus, it is and will remain an important tool to define the diagnostic significance of positive culture isolates or results from PCR testing. However, there are very few instances where the morphological characteristics of fungi are specific. Therefore, histopathologic diagnosis should be primarily descriptive of the fungus and should include the presence or absence of tissue invasion and the host reaction to the infection. The pathology report should also include a comment stating the most frequent fungi associated with that morphology as well as other possible fungi and parasites that should be considered in the differential diagnosis. Alternate techniques have been used to determine the specific agent present in the histopathologic specimen, including immunohistochemistry, in situ hybridization, and PCR. In addition, techniques such as laser microdissection will be useful to detect the now more frequently recognized dual fungal infections and the local environment in which this phenomenon occurs