Invasive lobular carcinoma is the most common special breast carcinoma subtype, with unique morphological (discohesive cells, single-cell files, targetoid pattern) and immunohistochemical (loss of E-cadherin and β-catenin staining) features. Moreover, ILC displays a poor response to neoadjuvant therapy, a different metastatic pattern compared to invasive breast carcinoma of no special type, as well as unique molecular characteristics. In addition to the classic variant of invasive lobular carcinoma, several other well-recognized variants exist, including classic, alveolar, tubulolobular, solid, pleomorphic, signet-ring, and mixed. Furthermore, three novel variants of invasive lobular carcinoma, i.e., with extracellular mucin production, papillary features, and tubular elements, have been described during the last decade. We herewith focus on the unique morphological and immunohistochemical characteristics of these novel varieties of invasive lobular carcinoma, as well as differential diagnostic considerations and potential diagnostic pitfalls, especially when dealing with biopsy specimens.

Background: Malignant Brenner tumors are rare ovarian tumors, accounting for less than 1% of malignant ovarian neoplasms. The aim of this manuscript is to systematically review the current literature concerning malignant Brenner tumors. Methods: We searched three medical databases (PubMed, Scopus, and Web of Science) for relevant articles published until 15 September 2023. Results: After applying inclusion and exclusion criteria, 48 manuscripts describing 115 cases were included in this study from the English literature. Conclusions: We analyzed the demographic, clinical, pathological, and oncological characteristics of 115 patients with malignant Brenner tumors. The statistical analysis showed that recurrence was marginally statistically significantly related to tumor stage and was more common in patients with ascites and in women with abnormal CA-125 levels; patients that were treated with lymphadenectomy had better disease-specific survival.

Background: Axillary lymph node metastasis is a rare stage IV ovarian carcinoma manifestation. This manuscript aims to systematically review the literature regarding axillary lymph node metastasis from ovarian carcinoma. Methods: We searched three medical internet databases (PubMed, Scopus, and Web of Science) for relevant articles published until 22 July 2023. Cases describing supraclavicular or intramammary lymph node metastases and concurrent metastasis to the breast were excluded. Results: After applying eligibility/inclusion and exclusion criteria, twenty-one manuscripts describing twenty-five cases were included from the English literature. Data were collected and analyzed regarding demographic, clinical, laboratory, radiological, histopathological, and oncological characteristics. Conclusions: We analyzed the clinical and oncological characteristics of patients with axillary lymph node metastasis from ovarian carcinoma, presented either as an initial diagnosis of the disease or as a recurrent disease. The analysis we performed showed a significant difference only in the serum CA-125 level (p = 0.004) between the two groups. There was no observed difference in womens’ survival.

Prostatic adenocarcinoma (PA) is the second most common malignancy in men globally. Signet-ring cell-like adenocarcinoma (SRCC) is a very rare PA subtype, with around 200 cases reported in the English literature. Histologically, the tumor cells show a vacuole compressing the nucleus to the periphery. Pagetoid spread in acini and ducts is usually related to metastases from urothelial or colorectal carcinomas, less commonly associated with intraductal carcinoma (IC); histologically, the tumor cells grow between the acinar secretory and basal cell layers. To our knowledge, we report the first prostatic SRCC (Gleason score 10, stage pT3b) associated with IC and pagetoid spread to prostatic acini and seminal vesicles. To our systematic literature review (PRISMA guidelines), it is the first tested case for both PD-L1 (<1% of positive tumor cells, clone 22C3) and mismatch repair system proteins (MMR) (MLH1+/MSH2+/PMS2+/MSH6+). We found no SRCC previously tested for MMR, while only four previous cases showed high expression of another PD-L1 clone (28-8). Finally, we discussed the differential diagnoses of prostatic SRCC.

Metastatic involvement of the thyroid occurs rarely, by either hematogenous spread or direct extension from adjacent organs. The most frequent metastatic tumors are clear cell, renal cell, lung, breast, and squamous cell carcinoma. The occurrence of osteosarcoma and papillary thyroid carcinoma in the same patient is rare, with only a few reported cases in the literature. On the other hand, only one case of osteosarcoma thyroid metastasis has so far been reported. We herewith present another case with metastatic osteosarcoma and multifocal papillary thyroid carcinoma presenting as a collision tumor and review the relevant literature.