A 53-year-old male patient was examined following incidental observation of an unsuspected mass on a chest X-ray. Computed tomography scan and videothoracoscopy revealed a solid pleural mass. A subsequent bone scan demonstrated multifocal radiotracer uptake within coarse intratumoral calcifications. Histopathological examination showed a benign mesenchymal proliferation with abundant long, fine projections consisting of mature cartilaginous nodules, mature fat and a dense lymphoplasmacytic infiltrate with lymphoid aggregates. The tumor was lined by an epithelial monolayer staining positive for cytokeratin and TTF-1, but not for calretinin, WT1 or podoplanin, thus indicating respiratory epithelium rather than mesothelium (Fig. 1). The tumor was labeled as pleural inflammatory chondroid hamartoma. Inflammation, a significant finding here, has not hitherto been reported in conjunction with hamartoma 1. The characteristic projections that we have described were previously reported with the odd term of placental transmogrification because its similarity with the chorionic villi 2. We postulate that this pseudo-villus appearance is a consequence of the combination of the metaplastic transformation of the mesenchymal tissue and the respiratory epithelial hyperplasia, all this due to a chronic inflammation. There was no evidence of any immune disorder, and the reason for this inflammatory infiltrate remains uncertain.
(A) Videothoracoscopic removal of pleuropulmonary tumor from anterior segment of left upper lobe. (B) The tumor displayed long villus-like papillae completely lined by epithelium. Note prominent cartilaginous stromal component H&E, 4×. (C) Dense lymphoplasmacytic infiltrate surrounding and intermingling with cartilaginous stroma. H&E, 20×. (D) Immunostaining for TTF-1 confirmed that villi were lined by respiratory epithelium. Immunohistochemistry, 40×.
Miguel A. Idoate serves as a consultant of Pathology Department of University Hospital Virgen Macarena and has no conflict of interest.
Inmaculada Sabariego-Arenas serves as a consultant of Thoracic Surgery Department of University Hospital Virgen Macarena and has no conflict of interest.
Jesús Machuca-Aguado serves as a consultant of Pathology Department of University Hospital Virgen Macarena and has no conflict of interest.
