TTF-1 is expressed in the alveolar epithelium and in the basal cells of distal terminal bronchioles. It is considered the most sensitive and specific marker to define the adenocarcinoma arising from the terminal respiratory unit (TRU). TTF-1, CK7, CK5/6, p63 and p40 are useful for typifying the majority of non-small-cell lung cancers, with TTF and CK7 being typically expressed in adenocarcinomas and the latter three being expressed in squamous cell carcinoma. As tumors with coexpression of both TTF-1 and p63 in the same cells are rare, we describe different cases that coexpress them, suggesting a histogenetic hypothesis of their origin. We report 10 cases of poorly differentiated non-small-cell lung carcinoma (PD-NSCLC). Immunohistochemistry was performed by using TTF-1, p63, p40 (∆Np63), CK5/6 and CK7. EGFR and BRAF gene mutational analysis was performed by using real-time PCR. All the cases showed coexpression of p63 and TTF-1. Six of them showing CK7+ and CK5/6− immunostaining were diagnosed as "TTF-1+ p63+ adenocarcinoma". The other cases of PD-NSCLC, despite the positivity for CK5/6, were diagnosed as "adenocarcinoma, solid variant", in keeping with the presence of TTF-1 expression and p40 negativity. A "wild type" genotype of EGFR was evidenced in all cases. TTF1 stained positively the alveolar epithelium and the basal reserve cells of TRU, with the latter also being positive for p63. The coexpression of p63 and TTF-1 could suggest the origin from the basal reserve cells of TRU and represent the capability to differentiate towards different histogenetic lines. More aggressive clinical and morphological features could characterize these "basal-type tumors" like those in the better known "basal-like" cancer of the breast.Diagnostics 2020, 10, 25 2 of 9 characterized by predominantly solid growth, formed by cells with large, eosinophilic cytoplasm, with a misleading tendency to keratinization or a pseudosquamoid morphology. Thus, histochemical detection of mucin and immunohistochemistry are often essential tests in differential diagnosis of NSCLCs, expanding the routine morphological examination.The combined use of antibodies TTF-1 and cytokeratin 7 (CK7) for ADC and p63 with high molecular weight keratins (CK5/6) for SCC provides a very reliable distinction between these two subtypes of non-small-cell carcinoma [1,2]. Recently, p40 has been considered the most specific marker of SCC [3]. SCC shows positive immunostaining for CK5/6, p63 and p40 (∆Np63) (with strong and widespread nuclear reaction) and negative immunostaining for TTF-1 and CK7. In contrast, ADC shows positive immunostaining for TTF-1 and CK7 and negative immunostaining for p63, p40 and CK5/6 [3,4]. Even if few ADCs may stain positively for p63, they show only a focal and weak positivity [5], while CK5/6 and p40 expression is usually absent. CK5/6-positive immunostaining is very unusual in ADCs, and even if it is present, in the absence of p63 and p40, it is not sufficient to support the squamous differentiation [3][4][5][6]. For SCC, p63 and CK...

Testicular plasmacytoma is a rare disease with few described cases in literature since 1939 when the first case was described. Testicular plasmacytoma can occur as first presentation disease or in multiple myeloma relapse. We report a case of a monorchid asymptomatic 70-year-old patient without previous multiple myeloma diagnosis with incidental discovery of right testicular mass who presented with rapid worsening of myeloma-related symptoms immediately after orchifunicolectomy. Diagnosis was made in our urology department and patient was referred to hematologist for continued therapy. We will discuss the case and review the literature.

(1) Background: Previous studies have reported a correlation between serum anti-Thyroglobulin-antibodies (TgAb) and papillary thyroid carcinoma. The aim of our study was to evaluate whether serum TgAb and anti-thyroid-peroxidase antibody (TPO) positivity was also related to pre-neoplastic histological changes such as papillary-like nuclear features (PLNF) and with the presence of lymphocytic infiltrate (LI) in thyroid surgical specimens. (2) Methods: The study was retrospectively carried out on 70 consecutively recruited patients who underwent thyroidectomy for benign process and whose TgAb and TPOAb values were retrieved from clinical records. Histological sections of thyroid surgical samples were revised, looking for PLNF and lymphocytic infiltrate. HBME1 expression was assessed by immunohistochemistry. (3) Results: Our results showed a significant association between TgAb, PLNF, and lymphocytic infiltrate. The presence of TgAb was highly specific, but less sensitive, in predicting the presence of PLNF (sensitivity = 0.6, specificity = 0.9; positive predictive value (PPV) = 0.88; negative predictive value (NPV) = 0.63). TgAb positivity showed a good association with the presence of lymphocytic infiltrate (sensitivity = 0.62, specificity = 0.9; PPV = 0.88 and NPV = 0.68). HBME1 immunoreactivity was observed in the colloid of follicles showing PLNF and/or closely associated with LI. (4) Conclusions: The presence of PLNF and LI is associated with serum TgAb positivity. The presence of TgAb and of LI could be triggered by an altered thyroglobulin contained in the HBME1-positive colloid, and could be a first defense mechanism against PLNF that probably represent early dysplastic changes in thyrocytes.

Background: Dumbbell tumors are typically benign schwannomas, neurofibromas, and meningiomas and only rarely there are malignant variants of these lesions or other malignant histotypes. Here, a 34-year-old male presented with a thoracic spinal dumbbell metastatic neuroendocrine carcinoma of unknown primary origin. Case Description: A 34-year-old male presented with 2 months of thoracic pain and progressive mid thoracic sensory loss. A post contrast thoracic MRI showed a dumbbell tumor localized between the T7 and T9 levels with extension laterally into the T7-T8 and T8-T9 foramina. The patient underwent a laminectomy for tumor resection following which his pain and gait improved. Histopathologically, the tumor demonstrated multiple rounded small cells with a Ki67 level around 30%, suggesting a malignant metastatic neuroendocrine tumor of unknown etiology. Conclusion: We successfully treated a 34-year-old male with a T7-T9 malignant spinal dumbbell neuroendocrine tumor of unknown etiology utilizing a decompressive laminectomy.