P1-166: Influence of tumour patterns in mixed-type adenocarcinoma on post-operative survival

Abstract

cm posterior mediastinal mas. With these findings, the patient was admitted for surgery. Physical examination, laboratory work-ups, and pulmonary function tests revealed normal results. The patient underwent thoracotomy of the right hemithorax. Intraoperatively, an elongated, pulsatile, fixed mass measuring 10 x 12 x 12 cm occupying the middle and posterior mediastinum extending from the azygous vein down to the diaphragm was noted. Microscopic examination of the resected tissues showed fibrocollagenous and adipose tissue fragments with several variably sized vascular channels with no evidence of malignancy. Large caliber arteries and veins were encountered and there was excessive bleeding hence, total excision of the mass was aborted. Results: Histopathologic examination revealed fibrocollagenous and adipose tissue with several irregular thick-walled vascular channels, nerve bundles, lymphocytic infiltrates, and hemorrhagic areas. The final anatomic diagnosis was: Fibrocollagenous tissue with proliferating blood vessels. A hemangioma and/or arteriovenous malformation is considered. Elastic stain and immunohistochemical staining were done. Thick-walled blood vessels were highlighted by elastic stain. The endothelial cells were immunoreactive to Factor VIII. S100 stained a nerve bundle and isolated neural cells. Positivity to CD31 was also observed on the cells lining the vessels. The immunohistochemical staining result supported the diagnosis of arteriovenous malformation. Conclusion:We report a rare case of posterior mediastinal arteriovenous malformation in a 27-year-old male. This is a case of an uncommon tumor in a very unusual location. The advent of immunohistochemistry has aided in classifying proliferating vascular tumors. The need to identify markers for the prognostic significance was emphasized, providing the opportunity to better inform our clinical colleagues. Due to the rarity of the disease, it posed a great dilemma which required a multidisciplinary approach. It provided a diagnostic and surgical challenge to our clinicians, radiologists, pathologists, and thoracovascular surgeons as well.

Pathologist and Molecular Biologist, ever the twain shall meet?

“…These prognostic effects are best seen in very small early adenocarcinomas. Studies of a broader range of surgically resected adeocarcinomas show less strong or absent associations [5,16,17].…”

“…Ninomiya et al may thus be quite justified in their statement that MP pattern may represent limited progression of BAC-pattern disease. MP pattern of adenocarcinoma is less strongly associated with survival in more advanced tumours [5,17]. The significance of the MP pattern in a broader range of adenocarcinomas, with and without alveolar destruction, needs to be elucidated but this will be difficult and should not be done to the exclusion of the other tumour components (solid and acinar disease) which will be variably present and also have metastatic potential.…”

Clinical relevance of the new IASLC/ERS/ATS adenocarcinoma classification

“…It became apparent that the vast majority of resected adenocarcinomas were ‘mixed’ and the other four categories were almost redundant. Subsequent data emerged, demonstrating that the predominant pattern in a mixed adenocarcinoma had prognostic relevance 27. At the same time, a micropapillary pattern of adenocarcinoma was recognised as being important 28 29.…”

Current issues in pulmonary adenocarcinoma

“…27 In small adenocarcinomas, a BAC component is a relatively good prognostic factor and the lack of a BAC component in lesions of 2 cm or less is a poor prognostic factor. 27 In small adenocarcinomas, a BAC component is a relatively good prognostic factor and the lack of a BAC component in lesions of 2 cm or less is a poor prognostic factor.…”

“…27,32 Non-mucinous adenocarcinomas with a prominent BAC component, including multiple satellite foci showing either a pure BAC pattern, or mixtures of BAC and stromally invasive disease are uncommon but well recognized. 27,32 Non-mucinous adenocarcinomas with a prominent BAC component, including multiple satellite foci showing either a pure BAC pattern, or mixtures of BAC and stromally invasive disease are uncommon but well recognized.…”