CytoLyt fixation impedes insulinoma-associated protein 1 (INSM1) immunoreactivity compared to formalin fixation.

INTRODUCTION: Insulinoma-associated protein 1 (INSM1) is an immunohistochemical marker commonly used to confirm cytomorphological concordant neuroendocrine tumors/carcinomas (NETs/NECs), demonstrating high utility in small samples. Previous reports have suggested comparable INSM1 staining in CytoLyt-fixed cell blocks and formalin-fixed surgical pathology specimens. This study aimed to assess INSM1 immunoreactivity using both fixation methods and investigate potential factors contributing to its variable expression. MATERIALS AND METHODS: A retrospective query was performed (03/31/21-05/31/22) for NET/NEC cases that had both formalin- and CytoLyt-fixed cell blocks. We collected clinical data and reporting of immunostains for each case. INSM1 staining was evaluated in both fixation methods, and reported as positive, negative, or equivocal. Equivocal INSM1 staining was further scored as a percentage of 1%-100% and intensity of weak (faint staining), moderate (darker staining), and strong (dense staining). RESULTS: Our search identified 20 cases from diverse body sites, including mediastinal lymph nodes (40%), pancreas (35%), lung (20%), and porta hepatis lymph nodes (5%). All cases exhibited a widespread positivity (over 90%) in formalin-fixed cell blocks. In contrast, CytoLyt fixed cells showed a negative stain in 65% of cases and 30% exhibited an equivocal positivity. CONCLUSIONS: While INSM1 is previously reported as a sensitive (75%-100%) and specific (82.7%-100%) marker for NET/NECs, our study found a reduced immunohistochemical staining in CytoLyt-fixed cell blocks. Consequently, false negative INSM1 immunohistochemical results in CytoLyt-fixed cell block material may pose a pitfall in the diagnosis of NET/NEC.

Klebsiella pneumoniae induces host metabolic stress that promotes tolerance to pulmonary infection.

K. pneumoniae sequence type 258 (Kp ST258) is a major cause of healthcare-associated pneumonia. However, it remains unclear how it causes protracted courses of infection in spite of its expression of immunostimulatory lipopolysaccharide, which should activate a brisk inflammatory response and bacterial clearance. We predicted that the metabolic stress induced by the bacteria in the host cells shapes an immune response that tolerates infection. We combined in situ metabolic imaging and transcriptional analyses to demonstrate that Kp ST258 activates host glutaminolysis and fatty acid oxidation. This response creates an oxidant-rich microenvironment conducive to the accumulation of anti-inflammatory myeloid cells. In this setting, metabolically active Kp ST258 elicits a disease-tolerant immune response. The bacteria, in turn, adapt to airway oxidants by upregulating the type VI secretion system, which is highly conserved across ST258 strains worldwide. Thus, much of the global success of Kp ST258 in hospital settings can be explained by the metabolic activity provoked in the host that promotes disease tolerance.

The Potential Prognostic and Therapeutic Implications of Prolactin Receptor and Growth Hormone-releasing Hormone Receptor Expression in Uterine Leiomyosarcomas.

The management of uterine leiomyosarcomas (uLMS) remains challenging. The rate of recurrence and metastasis is high, with 5-yr survival reaching only 40% to 50% in patients with tumor confined to the uterus (FIGO stage I or II). Prolactin receptor (PRLR) and growth hormone-releasing hormone receptor (GHRHR) have been implicated in the carcinogenesis of malignant tumors of the breast, endometrium, ovary, liver, and prostate. GHRHR antagonists inhibit in vitro growth of many human tumors and the expression of PRLR is associated with resistance to chemotherapy. The immunohistochemical expression of PRLR and GHRH in 24 primary and 2 recurrent uLMS was evaluated. Representative sections were stained with PRLR and GHRHR antibodies and immunoreactivity was calculated using H -score. The results were correlated with clinicopathologic data using Kaplan-Meier survival and multivariable Cox proportion hazard regression analyses. All tumors were positive for both markers with predominantly moderate to strong expression of PRLR (89%) and GHRHR (82%). Patients with tumors showing moderate to strong expression of PRLR were significantly less likely to achieve disease-free survival ( P =0.004) and significantly more likely to have a poor overall survival ( P =0.049). No significant difference in mean PRLR expression was found between tumors with higher mitotic counts (>20/10 hpf) and lower mitotic counts (20 or less/10 hpf). Furthermore, in 2 patients where the primary and recurrent tumors were tested, there was stronger expression of PRLR in the recurrence compared with the primary. This correlation was not found with GHRHR. Both PRLR and GHRHR may play a role in carcinogenesis in uLMS, as they do in other malignant neoplasms. To our knowledge, this study is the first evaluating the expression of these receptors in uLMS. Moderate or high expression of PRLR may serve as a prognostic marker associated with recurrences and increased mortality in uLMS patients.

Follow-up Findings in Postconservative Treatment Surveillance for Women With Cervical Adenocarcinoma In Situ.

OBJECTIVES: The risks of adenocarcinoma in situ (AIS) recurrence or progression after conservative treatment are uncertain. The aim of this study was to examine the role of high-risk human papillomavirus (hrHPV) and cytology in the posttreatment surveillance of AIS patients. MATERIALS AND METHODS: Follow-up results of hrHPV status, cytology results, and clinicopathological features of 207 patients were retrospectively analyzed, in whom AIS was initially treated by loop electrosurgical excision procedure (LEEP)/cone biopsy between September 2009 and June 2018. RESULTS: Among 207 patients diagnosed AIS on LEEP/cone biopsy, 30.9% (64/207) had positive margins. Persistent/recurrent AIS rate was substantially higher in the patients with positive margins than in those with negative margins (47.2% vs 9.3%, p < .001). Of 74 patients with hrHPV surveillance, 17 (17/74, 23.0%) were found to have positive hrHPV and 4 (4/17, 23.5%) had the persistent/recurrent AIS regardless of margin status. On the contrast, no AIS were found in negative surveillant hrHPV patients (23.5% vs 0%, p < .001). Lastly, 27.8% patients (22/79) were reported atypical glandular cells on surveillant cytology, and 9 persistent/recurrent AIS cases were further identified on second biopsy or hysterectomy with a positive detection rate of 40.9%. CONCLUSIONS: In this study, we concluded the positive margin on LEEP/cone biopsy in AIS patients was associated with a significantly greater risk of disease persistence or recurrence. The posttreatment surveillance by cytology and adjunct hrHPV would be an ideal strategy in predicting AIS persistence and recurrence, which will warrant further treatments.

Peritheliomatous pattern: A diagnostic clue for diagnosing metastatic melanoma in cytology.

BACKGROUND: A peritheliomatous pattern (PP) in tumors is characterized by a sheath of viable tumor cells closely surrounding a central blood vessel. In the authors' cytology practice, such a PP has been recognized in several metastatic melanoma specimens. The aim of this study was to evaluate the frequency of a PP in cytology samples of melanoma in comparison with other tumors. METHODS: Eighty archival fine-needle aspiration (FNA) cases of metastatic melanoma were compared with 65 control cases (35 poorly differentiated/metastatic carcinomas, 15 lymphomas, and 15 recurrent/metastatic/high-grade sarcomas). Cytologic findings were correlated with corresponding histologic specimens, which were available for 44 cases (55%) in the melanoma group and for 23 cases (35.38%) in the control group. All slides were examined for a PP and were semiquantitatively graded for comparison. RESULTS: A PP was present in 51.3% of the cytologic preparations (n = 41) among the melanoma group cases, whereas in the control group, a PP was present in only 3.1% of the cases (n = 2). A PP was present in 65.9% of melanomas with available histologic sections (n = 29) and in 8.7% of tissue samples from the control group (n = 2). A PP was seen more often in cell blocks than direct smear preparations (51.3% vs 40.0%) from patients with melanoma. CONCLUSIONS: The presence of a characteristic PP can be helpful in diagnosing melanoma in FNA samples because it was present in almost half of the metastatic melanoma cases in this study and was rarely present in other tumor types. A PP is easier to recognize and more often presents in cell blocks than aspirate smears. Ancillary studies such as immunohistochemistry are helpful for excluding other entities that may exhibit a PP.