Breast cancer is the leading cause of cancer death in the female population, despite advances in diagnosis and treatment. The highly heterogeneous nature of the disease represents a major obstacle to successful therapy and results in a significant number of patients developing drug resistance and, eventually, suffering from tumor relapse. Cancer stem cells (CSCs) are a small subset of tumor cells characterized by self-renewal, increased tumor-initiation capacity, and resistance to conventional therapies. As such, they have been implicated in the etiology of tumor recurrence and have emerged as promising targets for the development of novel therapies. Here, we show that the histone demethylase lysine-specific demethylase 1 (LSD1) plays an important role in the chemoresistance of breast cancer cells. Our data, from a series of in vitro and in vivo assays, advocate for LSD1 being critical in maintaining a pool of tumor-initiating cells that may contribute to the development of drug resistance. Combinatory administration of LSD1 inhibitors and anti-cancer drugs is more efficacious than monotherapy alone in eliminating all tumor cells in a 3D spheroid system. In conclusion, we provide compelling evidence that LSD1 is a key regulator of breast cancer stemness and a potential target for the design of future combination therapies.

Background/Aim: To evaluate the association between programmed cell death ligand 1 (PD-L1) expression on both tumor cells (TC) and inflammatory cells (IC), tumor infiltrating lymphocytes (TILs), CD3 + and CD8 + lymphocytes and other clinicopathological parameters in primary infiltrative breast cancer (IBC) of young women, a population shown to have a worse prognosis. Materials andMethods: A retrospective study was performed collecting data from patients younger than 40 years old. Forty-five young women with IBC were included. Whole tissue sections were used to evaluate all parameters. Results: Twenty percent (20%) of cases showed PD-L1 expression by tumor cells (PDL1TC) and 44.4% showed PD-L1 expression by immune cells (PDL1IC). Furthermore, 28.88% revealed high stromal TILs. PDL1TC and PDL1IC expression were significantly associated with tumor diameter and expression of estrogen (ER) and progesterone (PR) receptors and Ki67. PDL1TC expression was also associated with grade. High TILs were associated with tumor diameter, ER and Ki67 expression. PDL1TC, PDL1IC expression and TILs were associated with the density of CD3 + and CD8 + lymphocytes. Conclusion: Our results are similar to those of other age groups, as reported in the literature.

Diagnosis of odontogenic tumors can be challenging due to their rarity and diverse morphology, but when arising near the tooth, the diagnosis could be suspected. When their location is not typical, like inside the paranasal sinuses, the diagnosis is less easy. Maxillary ameloblastomas are exceedingly rare with only sparse information on their epidemiological, histological and genetic characteristics. The aim of this report is to thoroughly review the available literature in order to present the characteristics of this tumor. According to available data, maxillary ameloblastomas can occur in all ages but later than mandible ones, and everywhere within the maxillary region without necessarily having direct contact with the teeth. No sex preference has been shown. The most common histological patterns seen in this location are the follicular and plexiform ones. Maxillary ameloblastomas are locally aggressive neoplasms, thus therapy aims for excision including normal bone beyond the lesion. In contrast to mandible ameloblastomas, maxillary ones most commonly show mutations of the SMO gene. Furthermore, differential tumor diagnosis is thoroughly discussed in the present review. Odontogenic tumors are rare and can pose diagnostic difficulties for non-specialized pathologists. Nevertheless, when the location is typical, i.e. molar region and when the histology shows the characteristic features of odontogenic neoplasms, diagnosis could be straightforward. In locations outside the oral cavity or when rare histological variants are found, suspecting the correct diagnosis can be challenging. This is especially true for maxillary ameloblastomas, which are rare, possibly leading to low awareness of this neoplasm at this location and often show non-classical morphology, thus, rendering its diagnosis more complicated. Thus, the aim of this review is to define and thoroughly describe maxillary ameloblastomas based on the available literature after a short introduction in the entity of ameloblastoma.

Primary cutaneous Ewing sarcoma is a very rare entity with less than 100 cases reported in the literature, sharing the same morphological and immunohistochemical characteristics as their osseous counterparts. Herein, to the best of our knowledge, we report the first case in English literature of a molecularly confirmed Ewing sarcoma with diffuse and strong SOX10 immunoreactivity. This exceedingly rare immunohistochemical finding along with the rarity of this tumor could easily lead to a misdiagnosis with significant repercussions. Our case highlights the difficulty in diagnosing primary cutaneous Ewing sarcoma as well as the pivotal role molecular diagnostics can play in specific scenarios.

Among sarcomas with a round-cell morphology that lack rearrangement of the EWSR1 gene, rearrangements involving the CIC gene are the most common. In comparison with Ewing Sarcoma, CIC-rearranged sarcomas present at an older average age, arise almost exclusively in soft tissues, are clinically more aggressive, and are more likely to be resistant to the chemotherapy regimens used for Ewing sarcoma.CIC-rearranged sarcomas present more commonly in a deep location, and we suspect that superficial presentations may be under-recognized. In this case series, we report three of such cases. Overall, the morphology is similar to CIC-rearranged sarcomas of deeper locations. We hope to raise awareness among the dermatopathology community by expanding the differential of superficial tumors with round cell morphology. K E Y W O R D S

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Gastric metastasis from breast cancer occurs infrequently and causes non-specific symptoms, usually attributed to the underlying disease. Furthermore, endoscopic findings are almost identical to primary gastric cancer, making the immunohistochemical examination of biopsies necessary for diagnosis. We present the case of a 64-year-old woman who was diagnosed with lobular breast cancer 3 years ago and received chemotherapy with evidence of remission. The patient presented with dyspepsia and progressive dysphagia for the last 6 months, not responsive to PPI treatment. Upper endoscopy revealed partial occlusion of the cardio-esophageal junction and thickened gastric folds resembling linitis plastica. However, immunohistochemical analysis of endoscopic biopsies showed infiltration of gastric mucosa by lobular breast cancer cells, making the diagnosis of gastric metastasis. Therefore, clinicians’ awareness of possible gastric metastasis is warranted in patients with a history of advanced breast cancer and severe gastric symptoms.

Signet-ring cell carcinoma is a highly malignant adenocarcinoma consisting of cells characterized as cytoplasmic vacuoles filled with mucin. The most common primary location of this type of cancer is the stomach, but it may also be found in other organs such as prostate, testis, bladder, ovaries, or colon. To date, metastatic signet-ring cell carcinoma of unknown primary (CUP) site to the testis is an extremely rare entity in daily practice. Reviewing the literature, we have been able to detect only three cases of testicular metastases from CUP, two with histological diagnosis of a signet-ring cell carcinoma and one with an adenocarcinoma. In this short paper, we report a case of a 56-year-old man who presented to our Department with testicular mass and ascites. Following a standard diagnostic approach no primary tumor could be identified. CUP was the final clinical diagnosis, histologically characterized as poorly differentiated adenocarcinoma with signet-ring cells involving the peritoneum and the testicular structures.