Lung adenocarcinoma is characterized by marked heterogeneity and may be composed of an admixture of histologic growth patterns, including acinar, papillary, solid, and lepidic (bronchioloalveolar). Tumors displaying a prominent or predominant cribriform architecture are rare and most often confused for metastases from other organs. We report the clinical, histologic, immunohistochemical, and molecular features in 15 primary lung adenocarcinomas with a predominant cribriform histology. All patients were adults between 30 and 80 years of age (median: 64), and all but one reported a history of heavy cigarette smoking. All cases showed a predominant (470%) cribriform architecture that resembled a variety of tumors arising in other organs, including breast, prostate, ovary, pancreas, uterus, colon, and thyroid. Immunohistochemical stains showed a phenotype consistent with a primary lung tumor (ie, TTF1 þ /CK7 þ ), with negative results for other markers. Molecular analysis in six cases showed that none harbored an EGFR-activating mutation. KRAS mutation was detected in one case, and an ALK1 and ROS1 gene rearrangement were each detected in an additional two cases. Cribriform adenocarcinomas of the lung represent a distinctive histologic subtype of lung cancer that may be morphologically difficult to differentiate from metastases with a predominant cribriform architecture.

Dermatoscopy of melanocytic lesions has guided the decision of when or not to biopsy a lesion. The use of this tool has increased clinical examination's sensitivity and specificity in 89% and 96% respectively. However, dermatoscopic evaluation of amelanotic or hypomelanotic melanomas, as well as metastases, can be difficult. There is still no standardization for the analysis of these pathologies, which relies mostly on their vascular pattern. We describe the dermatoscopy of acral metastatic amelanotic melanoma.

; Larissa Cardoso Marinho 5 J Bras Patol Med Lab • v. 48 • n. 4 • p. 269-272 • agosto 2012 reLato de caso case report We present a rare case of thymoma in a 36-year old woman, who was initially diagnosed with severe myasthenia gravis and subsequently undergone surgical resection. During surgery tumor was found at the anterior mediastinum, tightly attached to the phrenic nerve, pleura and pericardium. Histological assessment showed large areas of sclerosis and fibrous collagenous tissue as well as islands of epithelial and lymphoid cells. Sclerosing thymoma, which is a rare subtype of thymoma (< 1%), was diagnosed, thus confirming the first report in Brazil. The patient showed partial improvement of symptoms associated with myasthenia gravis.