Anaplastic large cell lymphoma with ALK::ATIC fusion mimicking a histiocytic sarcoma debuting as an anterior thoracic soft tissue tumor with exceptional clinicopathological, morphological and molecular features.

A 56-year-old woman debuted with a palpable painless mass in the anterior thorax wall at the level of the second and third right parasternal intercostal space, which progressively increased in size over 5 months accompanied by localized skin rash, mild dyspnea and chest pain when changing position. Imaging studies showed a soft tissue mass measuring 75 × 62 mm and a density of 34 Hounsfield Units that had caused the lysis of the costal arches and grew expansively towards the anterior mediastinum, without identifying mediastinal adenopathies only by this imaging method. Core biopsy was performed, which was initially diagnosed as histiocytic sarcoma (HS); however, when the diagnostic panel was expanded to include molecular and NGS studies, the final diagnosis was anaplastic large cell lymphoma with ALK::ATIC fusion. Here, we report a very rare neoplasm with unusual clinical presentation, histopathology and molecular features.

[Large cell carcinoma of the lung with null immunophenotype: Case report & brief review]. / Carcinoma de células grandes de pulmón con inmunofenotipo nulo: reporte de caso y revisión breve de la literatura.

Large cell carcinoma of the lung with null-immunophenotype (LCC-NI) is a diagnostic entity that is especially uncommon now as it does not have any type of cell differentiation or its own molecular alterations. It presents an exceptional diagnostic challenge; indeed, the diagnosis is only possible with complete surgical excision and adequate immunohistochemical and molecular studies. We report the case of a 69-year-old male, with a history of long-term smoking who presented with pleuritic pain. A tumor in the upper lobe of the right lung was detected and removed by lobectomy. Histopathology revealed a neoplasm with large cell morphology without any specific immunophenotype, molecular or genomic rearrangements through next-generation sequencing (NGS) studies, which was diagnosed as LCC-NI.

Intestinal-type adenocarcinoma arising from a villous adenoma in the renal pelvis in the context of a kidney abscess: Case report.

Villous adenoma is a benign neoplasm with an exceptional presentation in the renal pelvis, hence very few cases have been reported. Herein we present the case of a patient who presented with left flank pain clinically suggestive of complicated pyelonephritis, culminating in simple nephrectomy with a villous adenoma in the renal pelvis as histopathological finding associated to the presence of a microscopic focus of intestinal-type adenocarcinoma.