BACKGROUND: Acinic cell carcinoma (AciCC) of the breast is a rare subtype of breast cancer. It was considered a low-grade triple-negative breast cancer (TNBC) with the potential to progress or transform into a high-grade lesion because of the molecular similarities with conventional aggressive TNBC in several genetic studies. Microscopically, the coexistence of classical low-grade and high-grade triple-negative components in breast AciCC is not uncommon. However, there is a scarcity of research on the comparative histopathological and genetic aspects of both components.
METHODS: A 34-year-old woman with a nontender mass in the upper outer quadrant of the left breast was initially diagnosed with a malignant small round cell tumor (undifferentiated or poorly differentiated carcinoma) based on a preoperative biopsy, which was later identified as breast AciCC with a high-grade solid component. Left breast-conserving surgery with sentinel lymph node biopsy was performed. Microscopically, the breast AciCC consisted of a classical acinic component and a high-grade component. The latter demonstrated a solid sheet-like pattern characterized by large, round, pleomorphic or vesicular nuclei, prominent nucleoli, and frequent mitotic activities. Classical acinic architectures focally merged together to form solid nests and transited into high-grade areas. Remarkably, in the high-grade lesion, conventional immunochemical markers for breast AciCC, such as α1-antitrypsin (AAT), Lysozyme (LYS), Epithelial membrane antigen (EMA), S100 protein (S100), and cytokeratin (CK) were negative, whereas cell cycle protein D1 (cyclin D1) and vimentin showed diffuse expression. Next‑generation sequencing (NGS) revealed that 43.5% of variants were identical in both components. Furthermore, PAK5 mutation; copy number (CN) loss of CDH1, CHEK1, and MLH1; and CN gains of CDK6, HGF, and FOXP1 were identified in the high-grade lesion. The patient was treated with eight cycles of adjuvant chemotherapy (epirubicin combined with cyclophosphamide) and radiotherapy after surgery, and she is currently alive for 43 months with no metastases or recurrences.
CONCLUSIONS: This case demonstrates a comparative analysis of the histopathological and genetic characteristics of classical low-grade and high-grade components of AciCC within the same breast. This information may serve as a morphological and molecular basis for further investigation into the molecular mechanisms underlying high-grade lesions in breast AciCC.

BACKGROUND: Therapeutic approach used for pancreatic ductal adenocarcinoma is usually translated also for the rarer acinar counterpart, which shows a different mutational landscape nevertheless. While dMMR/MSI-H status is rare in the ductal histotype, it appears to be more prevalent in pancreatic acinar cell carcinoma (PACC).
METHODS: We report the case of a patient with locally advanced MSI-H PACC in whom the treatment with the anti-PD-1 pembrolizumab, administered as third line, made possible surgical resection, achieving even an exceptional pathological complete response.
CONCLUSIONS: Treatment of PACC should be tailored based on the peculiar molecular features that distinguish PACC from ductal adenocarcinoma. Evaluation of potentially therapeutically targetable alterations should be mandatory in case of PACC diagnosis.

OBJECTIVE: The purpose of this work was to evaluate c-MYC gene amplification in the substrate of prostate acinar adenocarcinoma at various Gleason scores and various stages of the disease, taking into account the morphological characteristics of the tumor.
METHODS: The number of cases in the study was 82, including the control group - 12 cases. Morphological assessment included: determination of the total Gleason score, grading group, assessment of lymphovascular/perineural invasion, and architectural characteristics of the tumor. Gene amplification was assessed by FISH using the c-MYC (8q24)/SE8 probe.
RESULTS: In all cases of the study group, amplification of the c-MYC gene was detected in the tumor, with a significant difference from the control group (p<0.05). When assessing cases with 4-6 fold copies of the gene, significant differences were established between patients with stages II and III of the disease and stage IV (10.0 and 13.5 versus 30.0) (p<0.05). Cluster amplification of the c-MYC gene was detected with equal frequency in groups of patients with stages III and IV of the disease, while in stage II of the disease, the event almost did not occur (p<0.05). A significant increase in the level of c-MYC gene amplification was found in groups with advanced stages of the disease (p<0.02). Non-cluster amplification significantly distinguishes T4M0 and T4M1 stage patients from the rest with a significant increase in the score (p<0.05). In the metastatic stage of the disease, there was an increase c-MYC gene amplification compared to the non-metastatic stage (p<0.02). The copy number of the c-MYC gene was significantly higher in cases with perineural and lymphovascular invasion, as well as in cases of cribriform tumor organization (p<0.05).
CONCLUSIONS: Amplification of the c-MYC gene in prostate tumor cells is associated with advanced stages of the disease (T4M0 and T4M1) with an increase in the copy number of the gene during the metastatic stage of the process. It was found that increased amplification of the c-MYC gene distinguishes groups of patients whose tumors exhibit perineural and lymphovascular invasion, as well as a cribriform pattern of tumor organization.
UNASSIGNED: Оценка амплификации гена c-MYC в субстрате ацинарной аденокарциномы простаты (ААП) при различных показателях суммы Глисона и стадиях заболевания с учетом морфологических характеристик опухоли.
UNASSIGNED: Число случаев, включенных в исследование — 82, из них 70 пациентов с ААП и 12 человек — группа контроля. Морфологическая оценка включала определение суммарного показателя Глисона, градационной группы, оценку лимфоваскулярной/периневральной инвазии и архитектурных характеристик опухоли. Оценка амплификации гена выполнялась методом FISH с использованием зонда c-MYC (8q24)/SE8.
UNASSIGNED: Во всех случаях основной группы в опухоли обнаруживалась амплификация гена c-MYC с достоверным отличием от группы контроля (p<0,05). При оценке случаев с 4—6-кратной копийностью гена установлены достоверные различия между пациентами со II и III стадиями заболевания, а также с IV стадией (10,0 и 13,5 против 30,0) (p<0,05). Кластерная амплификация гена c-MYC обнаружена с равной частотой в группах пациентов с III и IV стадиями заболеваний, тогда как при II стадии заболевания событие почти не встречалось (p<0,05). Обнаружено значимое увеличение уровня амплификации гена c-MYC в группах с продвинутыми стадиями заболевания (p<0,02). Некластерная амплификация достоверно отличает пациентов стадий T4M0 и T4M1 от остальных со значительным повышением показателя (p<0,05). При метастатической стадии заболевания отмечалось увеличение амплификации гена c-MYC в сравнении неметастатической (p<0,02). Копийность гена c-MYC была достоверно выше в случаях с периневральной и лимфоваскулярной инвазией, а также при криброзной организации опухоли (p<0,05).
UNASSIGNED: Амплификация гена c-MYC в клетках опухоли простаты сопряжена с продвинутыми стадиями заболевания (T4M0 и T4M1) и с нарастанием копийности гена при метастатической стадии процесса. Обнаружено, что повышенная амплификация гена c-MYC отличает группы пациентов, в опухолях которых обнаруживаются явления периневральной и лимфоваскулярной инвазии, а также крибриформный паттерн организации опухоли.

OBJECTIVE: While several studies reported epidermal growth factor receptor (EGFR) expression in salivary gland cancer (SGC), results varied due to a lack of unified definition of EGFR positivity. In this study, we assessed the EGFR expression level using both EGFR positive score and cumulative EGFR score in the patients with SGC.
METHODS: Between January 2010 and April 2021, 102 patients with SGC who underwent surgical resection were reviewed retrospectively by immunohistochemistry. The membrane staining intensity was scored as follows: no staining (0), weak staining (1+), intermediate staining (2+), and strong staining (3+). The cumulative EGFR score was determined on a continuous scale of 0-300 using the formula:1 × (1+: percentage of weakly stained cells) + 2 × (2+: percentage of moderately stained cells) + 3 × (3+: percentage of strongly stained cells).
RESULTS: EGFR expression in SGC varied widely even among the same as well as different histopathological types. The average EGFR positive scores were 46.0 %, 55.7 %, 51.6 %, 1.0 %, 26.8 %, 50 %, and 76.8 % for mucoepidermoid carcinoma (MEC), salivary duct carcinoma (SDC), adenoid cystic carcinoma (AdCC), acinic cell carcinoma (AcCC), adenocarcinoma NOS (ACNOS), carcinoma ex pleomorphic adenoma (CAexPA), and squamous cell carcinoma (SqCC), respectively. The average cumulative EGFR scores were 82, 91, 80, 1, 52, 93, and 185 for MEC, SDC, AdCC, AcCC, ACNOS, CAexPA, and SqCC, respectively.
CONCLUSIONS: EGFR positive scores and cumulative EGFR scores in SGCs varied among the various histological types, and even in the same histological type. These scores may predict the clinical outcome of SGC treated with EGFR-targeting therapies, such as head and neck photoimmunotherapy, and need to be evaluated in future studies.

BACKGROUND: Thanks to technological advances, prostate cancer (PCa) can be diagnosed at a younger age. It is known that most of these patients are in the low-intermediate risk group, and the histological grade of the tumor increases in half of those undergoing radical prostatectomy (Rp) compared to their diagnostic biopsies. This is especially important in terms of active surveillance (AS) and/or the timely evaluation of curative treatment options in patients diagnosed at an early age. Our aim was to investigate clinical and histopathological parameters that may be associated with an increase in the histological grade of the tumor in patients with acinar adenocarcinoma who were diagnosed by transrectal ultrasound-guided biopsy (TRUS-Bx) and underwent Rp.
METHODS: A total of 205 patients with classical acinar adenocarcinoma diagnosed by TRUS-Bx without metastasis and who underwent Rp were grouped according to the D\'Amico risk classification. Age at diagnosis, serum prostate-specific antigen (PSA), PSA density, prostate volume, Prostate Imaging Reporting and Data System (PI-RADS) score, clinical stage, Gleason Grade Group (GGG), high-grade intraepithelial neoplasia in tumor-free cores (HGPIN) (single and ≥2 cores), perineural invasion (PNI), and lymphovascular invasion (LVI) was obtained. Additionally, GGG, pathological stage, lymph node metastasis, surgical margin positivity, and tumor volume obtained from Rp were evaluated. Comparisons were made between the case groups in which the tumor grade increased and remained the same, in terms of age, serum PSA, PSA density, HGPIN in tumor-free cores (single and ≥2 cores), PNI, and LVI in all biopsies (with or without tumors), as well as risk groups. In addition, the relationships of HGPIN in tumor-free cores (single and ≥2 cores), PNI, and LVI on TRUS-Bx with age, serum PSA and PSA density, tumor volume, surgical margin positivity, pathological stage, lymph node metastasis, and risk groups were examined separately.
RESULTS: Of the patients, 72 (35.1%) were in the low-risk group, 95 (46.3%) in the intermediate-risk group, and 38 (18.5%) in the high-risk group. Most of the patients with an increased histological grade (n = 38, 48.1%) were in the low-risk group (p < 0.05) and had an advanced median age. HGPIN in single and ≥2 tumor-free cores and PNI were more common in these patients (p < 0.01, p < 0.001, and p < 0.05, respectively). According to the multivariable analysis, advanced age (odds ratio [OR]: 1.087, 95% confidence interval [CI]: 1.029-1.148, p < 0.05), high serum PSA (OR: 1.047, 95% CI: 1.006-1.090, p < 0.05), HGPIN in ≥2 tumor-free cores (OR: 6.346, 95% CI: 3.136-12.912, p < 0.001), and PNI (OR: 3.138, 95% CI: 1.179-8.356, p < 0.05) were independent risk factors for a tumor upgrade. Furthermore, being in the low-risk group was an independent risk factor when compared to the intermediate- and high-risk groups (OR: 0.187, 95% CI: 0.080-0.437, p < 0.001 and OR: 0.054, 95% CI: 0.013-0.230, p < 0.001, respectively). The HGPIN diagnosis was more common in the low- and intermediate-risk groups. Advanced age at diagnosis, high serum PSA and PSA density values were associated with PNI on TRUS-Bx. High serum PSA and PSA density values were associated with LVI on TRUS-Bx. Surgical margin positivity was higher in cases with PNI and LVI detected by TRUS-Bx. HGPIN in ≥2 tumor-free cores, PNI, and LVI on TRUS-Bx were associated with a higher rate of lymph node metastases.
CONCLUSIONS: In patients diagnosed with acinar adenocarcinoma, the presence of HGPIN even in a single tumor-free core on TRUS-Bx was found to be significant in terms of showing an increase in the histological tumor grade in Rp. The diagnosis of HGPIN in ≥2 tumor-free cores on TRUS-Bx was determined as an independent risk factor for an increased Gleason score after Rp. Furthermore, an advanced age, a high serum PSA value, being in the low-risk group, and the presence of PNI were associated with a tumor upgrade. HGPIN in ≥2 tumor-free cores, PNI, and LVI were also associated with lymph node metastasis. Therefore, the diagnosis of HGPIN should be signed out on pathological reports.

Cancer-associated stroke is an evolving subgroup of embolic strokes of undetermined source. A man in his mid-20s with progressive follicular variant acinic cell carcinoma of the parotid was admitted because of new onset left-sided weakness. Neuroimaging confirmed a right middle cerebral artery infarction. After extensive diagnostics, stroke aetiology was deemed from cancer-induced hypercoagulability. Questions which arose regarding his management included (1) What was the best antithrombotic for secondary stroke prevention? (2) What was his risk for intracranial or tumorous bleeding once antithrombotics had been started? (3) How many days post-stroke could the antithrombotic be initiated? and (4) When could he be cleared for palliative chemotherapy and whole brain irradiation? The approach to address the abovementioned questions in the management of a rare cancer complicated by stroke is presented. Although treatments are guided by known pathomechanisms, additional studies are needed to further support current treatment strategies for this subgroup of patients.

While acinic cell carcinoma (AciCC) can undergo high-grade transformation (HGT) to high-grade adenocarcinoma or poorly differentiated carcinoma, other morphologies such as spindle cell/sarcomatoid carcinoma are rare and not well-characterized. We herein report a novel case of AciCC with squamoglandular and chondrosarcomatous HGT mimicking a so-called \'carcinosarcoma ex-pleomorphic adenoma\'. The patient is an 81-year-old male with a two-month history of neck swelling and referred otalgia who presented with a left parapharyngeal space mass extending into retropharyngeal space and pterygoid muscles. On resection, the tumor showed considerable morphologic diversity with high-grade serous and mucous acinar components as well as cribriform to solid apocrine-like components with comedonecrosis and squamous differentiation, all of which were embedded in a chondromyxoid background ranging from paucicellular and bland to a high-grade chondrosarcoma/pleomorphic sarcoma-like appearance. Only a minor conventional AciCC component was noted. Immunostains were negative for AR and only focally positive for GCDFP-15 arguing against a true apocrine phenotype, while PLAG1 and HMGA2 were negative arguing against an antecedent pleomorphic adenoma. On the other hand, SOX-10, DOG-1 and PAS after diastase highlighted serous acinar differentiation, and mucicarmine, and NKX3.1 highlighted mucous acinar differentiation. NR4A3 immunohistochemical staining and NR4A3 fluorescence in situ hybridization were positive in the carcinomatous and sarcomatoid components while sequencing analysis of both components revealed identical alterations involving TP53, PIK3CB, ARID1A, and STK11. This unique case warrants caution in designating all salivary sarcomatoid carcinomas with heterologous elements as part of the \'carcinoma ex-pleomorphic adenoma\' family.

Pancreatic acinar cell carcinoma (PACC) is a very rare subtype of pancreatic cancer. Due to small number of patients, no standard chemotherapy protocol has been established. We experienced an extremely rare case of PACC with liver metastasis that showed a pathological complete response after modified FOLFIRINOX (mFFX) therapy. A 42-year-old man who underwent distal pancreatectomy for an 80 mm tumor at the pancreatic tail 3 years ago was referred to our hospital in September 2017 for the treatment of a recurrent liver tumor. Percutaneous biopsy revealed an acinar-neuroendocrine carcinoma, similar to the surgical specimen. He received eight cycles of irinotecan plus cisplatin chemotherapy. However, the tumor increased in size, and treatment was switched to mFFX therapy. The tumor in the liver shrank remarkably after nine cycles of mFFX therapy. Conversion surgery was selected, and the patient underwent hepatic left and caudate lobectomy 8 months after administration of mFFX. The resected specimen showed no viable tumor cells, indicating a pathological complete response. The histological diagnosis was reconsidered, and PACC was finally diagnosed via an additional immunohistological review. The patient has remained well with no recurrence for 6 years after surgery. This study is the first to report a case of pathological complete response with mFFX therapy for the recurrence of PACC.

Pancreatic acinar cell carcinoma (PACC) is a rare cancer with no specific treatment. The treatment and chemotherapy for PACC are selected according to pancreatic ductal adenocarcinoma (PDAC). Herein, we describe a recurrent PACC case of an older adult patient. The patient was treated with systemic chemotherapy, chemoradiotherapy, and maintenance therapy based on the pathologic germline BRCA2 variant, resulting in long-term survival. The pathogenic BRCA variant is detected more frequently in patients with PACC than in those with PDAC. The BRCA variant significantly impacts treatment selection and prognosis; therefore, early genomic analysis is recommended when treating PACC.

A 73-year-old Japanese man with a history of distal biliary cancer treated by pancreatoduodenectomy developed pancreatic acinar cell carcinoma (PACC) treated by remnant pancreatectomy and adjuvant chemotherapy. Thirteen months after surgery, multiple liver metastases developed and FOLFOX chemotherapy was initiated. Based on the PACC diagnosis and a positive family history for breast and ovarian cancer genetic testing was performed which revealed a pathogenic germline BRCA2 variant (c.8629G > T, p.Glu2877Ter). Olaparib therapy was initiated and the metastases responded well (partial response). PACC is a BRCA2-associated cancer which may respond well to PARP inhibitors.