Depth-Specific Hypoxic Responses to Spreading Depolarizations in Gyrencephalic Swine Cortex Unveiled by Photoacoustic Imaging.

Spreading depolarizations (SDs) are a marker of brain injury and have a causative effect on ischemic lesion progression. The hemodynamic responses elicited by SDs are contingent upon the metabolic integrity of the affected tissue, with vasoconstrictive reactions leading to pronounced hypoxia often indicating poor outcomes. The stratification of hemodynamic responses within different cortical layers remains poorly characterized. This pilot study sought to elucidate the depth-specific hemodynamic changes in response to SDs within the gray matter of the gyrencephalic swine brain. Employing a potassium chloride-induced SD model, we utilized multispectral photoacoustic imaging (PAI) to estimate regional cerebral oxygen saturation (rcSO2%) changes consequent to potassium chloride-induced SDs. Regions of interest were demarcated at three cortical depths covering up to 4 mm. Electrocorticography (ECoG) strips were placed to validate the presence of SDs. Through PAI, we detected 12 distinct rcSO2% responses, which corresponded with SDs detected in ECoG. Notably, a higher frequency of hypoxic responses was observed in the deeper cortical layers compared to superficial layers, where hyperoxic and mixed responses predominated (p < 0.001). This data provides novel insights into the differential oxygenation patterns across cortical layers in response to SDs, underlining the complexity of cerebral hemodynamics post-injury.

Pseudohyperplastic prostatic carcinoma in simple prostatectomy.

Pseudohyperplastic carcinoma (PHPC) is a prostatic neoplasm that can be easily mistaken for nodular hyperplasia or atypical adenomatous hyperplasia. To determine the frequency and clinicopathologic characteristics of PHPC, we reviewed 200 simple prostatectomy specimens. We found 3 cases (1.5%) of PHPC. The tumors were small and ranged in size from 4 to 6 mm. Two of them were erroneously diagnosed as benign glandular proliferations in the original interpretation. Their histologic aspect at low magnification showed nodules of well-differentiated medium-sized glands with cystic dilation in a tight arrangement that imparted a benign appearance. Corpora amylacea were found in 2 cases. However, the lining cells showed nucleomegaly and prominent nuclei in most of the neoplastic glands, and the high-molecular-weight keratin (34BE12) immunostain revealed absence of basal cells. α-Methylacyl-CoA-racemase was positive in 2 cases. In one case, a small focus of moderated acinar adenocarcinoma was found adjacent to the pseudohyperplastic glands facilitating the diagnosis. The 3 patients are disease-free 3 and 4 years after surgery probably because of the small size of the tumors; however, it must be emphasized that most PHPC are considered moderately differentiated and potentially aggressive neoplasms.

Neuroendocrine metastatic tumors of the liver resembling hepatocellular carcinoma.

Certain neuroendocrine tumors (NET) metastasized to the liver can resemble hepatocellular carcinoma (HCC) in cytological needle biopsy. Experience concerning the histologic characteristics of metastatic NET resembling HCC in core needle hepatic biopsies has been scarce. The aim of this study is to describe the histological criteria in seven metastatic NET that resembled HCC in core needle hepatic biopsy. From a total of 285 needle biopsies with primary or metastasized hepatic neoplasms, seven cases were selected originally diagnosed as HCC or HCC vs. NET metastasized to the liver. Fourteen needle biopsies of hepatocellular carcinomas were also studied for comparative purposes. In all of these neoplasms the diagnosis of endocrine tumor was confirmed by immunohistochemical studies and the following information was recorded: age, sex, radiological alterations, primary site of the NET, and follow-up. The following histological data were also recorded: fibrotic stroma associated or not with the neoplastic cells, growth pattern, form of the cells, cellular size, mitotic figures, nucleomegaly, apparent nucleoli, chromatin in salt and pepper, plasmacytoid cells, intranuclear inclusions, and biliary pigment. In conclusion, these characteristics were common in metastasized neuroendocrine tumors: extensive stromal fibrosis, slight to moderate atypia, hyperchromatic nuclei, plasmacytoid cells, and thin delicate strands of fibrovascular tissue supporting larger acinar groups of net cells. HCC had a more infrequent fibrotic stroma, moderate to marked atypia, and in some biopsies biliary pigment, intranuclear inclusions, and clear cells.