Histology of Bronchiolar Tumor Spread Through Air Spaces.

The clinical significance of lung tumor spread through air spaces (STAS) has been extensively studied, and is recognized as a unique pattern of invasion. Previous studies of STAS have focused primarily on STAS in alveolar spaces, whereas STAS in the bronchiolar spaces (bronchiolar STAS) has been described in only a few case reports only. Here, we examined 306 cases of primary lung adenocarcinoma and found that bronchiolar STAS was present in 18%. Bronchiolar STAS was associated with an inferior prognosis, more advanced stage, and higher histologic grade. No significant difference in clinicopathological factors or prognosis was observed between cases with bronchiolar STAS and those with alveolar STAS alone. Notably, bronchiolar STAS often occurred simultaneously with alveolar STAS and endobronchial spread of adenocarcinoma, particularly when bronchiolar STAS was present outside the main tumor. We also identified cases where bronchiolar STAS and endobronchial spread of adenocarcinoma occurred simultaneously in the same bronchi or bronchioles located outside the main tumor, as well as cases with bronchiolar STAS adjacent to intrapulmonary metastatic nodules. Our results highlight the significant role of bronchiolar STAS in the aerogenous spread of adenocarcinoma cells. Bronchiolar STAS can be regarded as a histologic variant of alveolar STAS. This study also supports the idea that STAS is not a tissue processing artifact, but a true biological process with clinical implications, offering histologic evidence of aerogenous spread in lung adenocarcinoma.

Primary Cutaneous NUT Carcinoma: Clinicopathologic and Genetic Study of 4 Cases.

WHO Classification of Skin Tumors, fifth edition (2023) has newly described primary cutaneous NUT carcinoma; however, information on this cancer type remains scarce. Herein, we performed clinicopathologic and genetic analyses of 4 cases. Four elderly women (median age 77 y, range: 68 to 82 y) were included. The median tumor size was 12.5 (10 to 40 mm). Tumors were located on the scalp, temple, thigh, and palm. Two (50%) patients presented with regional lymph node metastases. Neither distant metastasis nor mortality was observed during patient follow-up of 10.5 (3 to 15) months. Sanger, panel DNA and whole-exome RNA sequencing revealed BRD3::NUTM1 (n=2) and BRD4::NUTM1 (n=2) fusions. Histology of BRD3-rearranged tumors revealed an epidermal connection, relatively small tumor nests, and ductal or intracytoplasmic luminal formation, whereas that of BRD4-rearranged tumors revealed large solid nests comprising discohesive tumor cells. NUT, cytokeratins, p63, EMA, TRPS1, c-MYB, CD56, and INSM1 were immunoexpressed to varying degrees in all (100%) tumors. Furthermore, diffuse SOX10 expression was common (3/4, 75%). The literature review of five previously described cases revealed women predominance, no recurrence, frequent BRD3::NUTM1 fusions, and histology of ductoglandular structures. Our study findings and literature suggest elderly women predominance, relatively frequent BRD3::NUTM1 fusions, histopathologic ductoglandular differentiation, absence of abrupt keratinisation, and a characteristic immunoprofile in primary cutaneous NUT carcinoma, unlike in that of other organ. No distant metastasis or disease-associated mortality was seen in all cases with limited follow-up.

Endobronchial spread of adenocarcinoma is a distinct pattern of invasion and associated with inferior clinical outcomes in lung adenocarcinoma.

AIM: The spread of lung adenocarcinoma cells into the bronchi and bronchioles is not well documented. We termed this histological finding "endobronchial spreading of adenocarcinoma" (EBSA) and investigated its prevalence and clinical significance. METHODS AND RESULTS: We reviewed 320 resected specimens from patients diagnosed with invasive adenocarcinoma, and EBSA was observed in 144 patients (45%). EBSA was significantly associated with advanced pathological stage, higher histological grade, larger tumour invasion, lymphovascular infiltration, and spread through air spaces. Patients with EBSA had significantly shorter relapse-free survival (RFS) and cancer-specific survival (CSS) in univariate analysis (P < 0.001). In a subgroup analysis of patient with small-sized (invasion size ≤30 mm) adenocarcinoma in the localized stage, EBSA was an independent inferior prognostic indicator in multivariate analysis. In a subgroup analysis of patients with small-sized Grade 1 nonmucinous adenocarcinoma (n = 61), EBSA was observed in 11 patients, and the presence of EBSA was associated with significantly shorter RFS and CSS (P = 0.026 and P = 0.001, respectively). CONCLUSION: Our results demonstrated that EBSA is a significant risk factor for disease recurrence and cancer-related deaths. EBSA can be regarded as a distinctive pattern of invasion and its recognition can be beneficial in the diagnosis of lung adenocarcinoma.

Diagnostic Utility of STAT6 and pSTAT6 Immunohistochemistry for Distinguishing Classic Hodgkin Lymphoma and Peripheral T-Cell Lymphoma With Hodgkin and Reed-Sternberg-like Cells.

Peripheral T-cell lymphomas (PTCLs), particularly nodal lymphomas of T-follicular helper cell origin, may include Hodgkin/Reed-Sternberg (HRS)-like cells in their microenvironment. These HRS-like cells are morphologically indistinguishable from HRS cells of classic Hodgkin lymphoma (CHL). Therefore, PTCLs with HRS-like cells pose a differential diagnosis vis-à-vis CHL. A previous study reported that, in contrast to HRS cells, programmed death-ligand 1 (PD-L1) expression is rare in HRS-like cells of PTCLs and suggested that PD-L1 immunohistochemistry is useful to differentiate HRS cells and HRS-like cells. In this study, we analyzed 21 patients with PTCL with HRS-like cells and 34 patients with CHL and assessed the diagnostic utility of STAT6, pSTAT6, and pSTAT3 immunohistochemistry in distinguishing HRS cells from HRS-like cells. In addition, we also performed PD-L1 immunohistochemistry to reconfirm its utility in distinguishing the 2 diseases. Compared with HRS cells in CHLs, HRS-like cells in PTCLs showed significantly less positivity for STAT6 (9.6% vs. 70%, P <0.001), pSTAT6 (9.6% vs. 70%, P <0.001), and PD-L1 (9.6% vs. 85%, P <0.001). Thus, we reconfirmed the diagnostic utility of PD-L1 immunohistochemistry in distinguishing CHLs from PTCLs with HRS-like cells. In contrast, both HRS-like and HRS cells were highly associated with pSTAT3 expression, with no significant difference in positive cell frequency (86% vs. 91%, P =0.66). On the basis of these findings, we conclude that, in addition to PD-L1, STAT6 and pSTAT6 immunohistochemistry are helpful diagnostic tools to distinguish CHLs from PTCLs with HRS-like cells.

Seborrheic Keratosis With Malignant Transformation (Invasive or Noninvasive Squamous Cell Carcinoma Arising in Seborrheic Keratosis): A Clinicopathologic and Immunohistochemical Study of 11 Cases.

ABSTRACT: Seborrheic keratosis is a common benign neoplasm composed of basaloid keratinocytes. However, little is known about the malignant transformation of the tumor. Eleven cases of seborrheic keratosis with malignant transformation were analyzed. The 11 patients included 5 male patients and 6 female patients with a median age of 75 years at diagnosis (68-90 years). The tumors arose at various sites from the scalp (n = 3) to the lower leg (n = 2). The median tumor size was 12 (10-32) and 40 (20-75) mm in 7 noninvasive and 4 invasive cases, respectively. One patient exhibited in-transit skin metastasis. Histopathology of the malignant components resembled porocarcinoma or inverted follicular keratosis. Bowenoid and pagetoid spreading was frequently observed. The malignant components expressed cytokeratin 5/6 (100%) and GATA3 (73%), but not cytokeratin 7 (0%), cytokeratin 19 (9%), BerEP4 (0%), c-kit (0%), and NUT (0%). No significant immunoreactivity of YAP1 was observed in any of the cases. Mutant-type immunostaining of p53 and PTEN was observed in 91% and 82% of the cases, respectively. An increase in p16 expression was seen in 6 (86%) of the 7 cases with noninvasive carcinoma, although a loss of p16 immunoexpression was seen in the invasive carcinoma component in 3 (75%) of the 4 cases. This study demonstrated that seborrheic keratosis can undergo malignant transformation, particularly in large-sized lesions in elderly patients. Malignant components mimic porocarcinoma or inverted follicular keratosis. Malignant transformation induced by TP53 and PTEN mutations and tumor invasion by CDKN2A inactivating mutations are suggested in this study.

TGFB1 mRNA expression is associated with poor prognosis and specific features of inflammation in ccRCC.

To determine whether TGFB1 affects the immune microenvironment of ccRCC, we investigated the association between TGFB1 expression and clinicopathological features. Tissue microarray was generated from 158 total or partial nephrectomy samples and 12 tumor-adjacent normal kidney tissue. TGFB1 expression was assessed by RNA in situ hybridization and quantified using ImageJ software. TGFB1 was significantly upregulated in ccRCC tissue than in normal kidney tissues (P = 1.03 × 10-9). Tumors with a high WHO/ISUP grade had higher TGFB1 expression levels (P = 7.05 × 10-3). Of 139 patients with localized ccRCC and whose follow-up data were available, those in the TGFB1-high group displayed significantly shorter relapse-free survival than those in the TGFB1-low group (P = 0.0251). TGFB1 expression was significantly upregulated in patients who developed distant metastasis after surgery (n = 12) than in patients without metastasis (n = 127; P = 0.00167). TGFB1 expression positively correlated with the number of PD-L1-positive cells in the tumor stroma (P = 0.0206, ρ = 0.163). Furthermore, TGFB1 expression was associated with the formation of tertiary lymphoid structures. TGF-ß1 is a prognostic indicator of worse outcome for ccRCC and might be a therapeutic target in advanced ccRCC. Our data provide new insights into the association between tumor biology and tumor microenvironment in ccRCC.

Prevalence and Clinicopathologic Features of Intestinal Perforation Caused by Segmental Absence of the Intestinal Musculature in Adults.

Segmental absence of the intestinal musculature (SAIM) can cause intestinal perforation in adults. However, its prevalence and clinicopathologic features have not been well-described. This study aimed to determine the prevalence of SAIM-associated perforation and characterize its clinicopathologic features. We retrospectively examined 109 cases of intestinal perforation that underwent surgical resection from January 2009 to December 2019. SAIM was defined as the complete absence of the muscularis propria without extensive inflammation and fibrinous exudation around the perforation. SAIM was the second most frequent cause of perforation (26 cases: 24%), the most frequent cause being related to diverticulitis (39 cases: 36%). The most common site was the sigmoid colon (12 cases: 46.2%). The younger group (aged below 65 y) exhibited more frequent perforation of the upper segments of the gastrointestinal tract (from the duodenum to the descending colon) than the older group (65 y and above) (P=0.0018). No patients developed recurrence. The most common gross features were well-defined circular or small punched-out lesions, and the histologic features were complete absence of the muscularis propria and absence of hemorrhage and necrosis around the area of perforation. The characteristic features of SAIM were unique and their prevalence was higher than previously reported. The precise recognition of SAIM can aid in understanding the cause of perforation and avoiding further unnecessary examinations.

Markedly Effective Steroid Treatment of Three Patients with Allergy-related Jackhammer Esophagus.

We experienced marked efficacy with steroid treatment of three patients with jackhammer esophagus (JHE). An esophageal biopsy revealed eosinophilic esophagitis (EoE) in two patients. One of the patients without EoE had eosinophilia and an increased serum immunoglobulin E level, and endoscopic ultrasonography revealed thickening of the esophageal muscularis propria. Esophageal manometry was used to diagnose all cases of JHE. Treatment consisted of steroid administration, which improved the symptoms and resolved the esophageal muscularis propria thickening in all patients. The esophageal manometry findings also normalized following treatment. Allergic diseases, including EoE, were assumed to have caused JHE.

Automated acquisition of explainable knowledge from unannotated histopathology images.

Deep learning algorithms have been successfully used in medical image classification. In the next stage, the technology of acquiring explainable knowledge from medical images is highly desired. Here we show that deep learning algorithm enables automated acquisition of explainable features from diagnostic annotation-free histopathology images. We compare the prediction accuracy of prostate cancer recurrence using our algorithm-generated features with that of diagnosis by expert pathologists using established criteria on 13,188 whole-mount pathology images consisting of over 86 billion image patches. Our method not only reveals findings established by humans but also features that have not been recognized, showing higher accuracy than human in prognostic prediction. Combining both our algorithm-generated features and human-established criteria predicts the recurrence more accurately than using either method alone. We confirm robustness of our method using external validation datasets including 2276 pathology images. This study opens up fields of machine learning analysis for discovering uncharted knowledge.