Histological features of a micronodular pneumocyte hyperplasia (MPH)-like lesion and adenocarcinomas.

<p><b>(A)</b> The sectioned surface of LP4-T1 is shown. The arrows indicate the white nodule that corresponds to an MPH-like lesion. <b>(B)</b> Hematoxylin and eosin (HE) staining of the MPH-like lesion. The lesion borders on the interlobular septum (ILS), indicated by arrowheads. <b>(C)</b> Further magnification of the lesion. Plump pneumocytes have enlarged nuclei that lack overt atypia and mitosis. The alveolar septa are thickened with dense fibers. <b>(D)</b> Computed tomography of LP1 demonstrates multiple cysts and a ground-glass opacity lesion indicated by arrows. <b>(E)</b> HE staining of the papillary adenocarcinoma (LP1-T1). A star indicates the cyst infiltrated by cancer cells. Inset: Higher magnification of the lesion. <b>(F)</b> HE staining of the micropapillary adenocarcinoma (LP2-T1). Inset: Higher magnification of the lesion.</p

Summary of clinical information.

<p>Summary of clinical information.</p

Summary of histology, gene mutations and immunostaining.

<p>Summary of histology, gene mutations and immunostaining.</p

An introduction to the WHO 5th edition 2022 classification of testicular tumours

The 5th edition of the World Health Organisation ‘blue book’ was recently published and includes a comprehensive update on testicular tumours. This builds upon the work of the 4th edition, retaining its structure, and main nomenclature, including the use of the term ‘germ cell neoplasia in situ’ (GCNIS) for the preinvasive lesion of most germ cell tumours and division from those not derived from GCNIS. While there have been important developments in understanding the molecular underpinnings of testicular cancer, this updated classification paradigm and approach remains rooted in morphology. Nomenclature changes include replacement of the term ‘Primitive neuroectodermal Tumour’ by ‘Embryonic Neuroectodermal Tumour’ based on the non-specificity of the former term and to separate these tumours clearly from Ewing sarcoma. Seminoma is placed in a germinoma family of tumours emphasising relation to those tumours at other sites. Criteria for the diagnosis of ‘teratoma with Somatic transformation’ have been modified to not include variable field size assessments. The word ‘carcinoid’ has been changed to ‘Neuroendocrine Tumour’ with most examples in the testis now classified as ‘Prepubertal Type Testicular Neuroendocrine Tumour’. For sex cord stromal tumours, the use of mitotic counts per high power field has been changed to per mm2 for malignancy assessments, and the new entities, ‘Signet Ring stromal Tumour’ and ‘Myoid Gonadal Stromal tumour’, are defined. Well-differentiated papillary mesothelial tumour has now been defined as tumour type with a favourable prognosis. Sertoliform Cystadenoma has been removed as an entity from testicular adnexal tumours and placed with Sertoli cell tumours

Expression of phospho-mTOR (p-mTOR), phospho-S6 (p-S6), and <i>FLCN</i> in BHD lung neoplasms.

<p><b> (A)-(C)</b> The micropapillary adenocarcinoma (MPAC) (A), adenocarcinoma <i>in situ</i> (AIS) (B), and micronodular pneumocyte hyperplasia (MPH)-like lesion (C) show positive immunostaining for p-mTOR (left) and p-S6 (right). Lower p-mTOR and p-S6 staining intensities are observed in the MPH-like lesion compared to the adenocarcinomas. <b>(D)-(F)</b> The MPAC (D), AIS (E), and MPH-like lesion (F) are diffusely immunostained for <i>FLCN</i>.</p

Sequence analysis of <i>FLCN</i>, <i>EGFR</i>, and <i>KRAS</i> in BHD lung neoplasms.

<p><b> (A)</b> Germline and somatic <i>FLCN</i> status in 3 representative cases with different mutation patterns are shown. Control normal sequences are shown on the left. Germline mutations are shown on the middle. The somatic status of <i>FLCN</i> in microdissected neoplasms are shown on the right. <b>(B)</b> The papillary adenocarcinoma (PAC) had a heterozygous missense mutation (L858R) in <i>EGFR</i> (indicated by an arrow). <b>(C)</b> The micropapillary adenocarcinoma (MPAC) had a heterozygous missense mutation (G12D) in <i>KRAS</i> (right, indicated by an arrow).</p