Predominantly or exclusively dopamine-secreting pheochromocytoma and paraganglioma are very rare. We report a 64-year-old woman with an adrenal incidentaloma. She was normotensive and had no symptoms of catecholamine excess. The 24-hour urine catecholamine level showed normal norepinephrine (122.9 μg/day), normal epinephrine (24.3 μg/day), and markedly elevated dopamine (148 212.4 μg/day). ¹²³I-metaiodobenzylguanidine (MIBG) scintigraphy revealed tumor uptake. After α-blockade as preoperative management, she successfully underwent laparoscopic left adrenalectomy and was finally diagnosed with an exclusively dopamine-secreting pheochromocytoma. The tumor was histologically comprised of small polygonal cells with high cellularity and was immunohistochemically positive for all 3 catecholamine-synthesizing enzymes: tyrosine hydroxylase (very weak), dopamine β-hydroxylase (heterogeneous), and phenylethanolamine N-methyltransferase (very weak). Electron microscopy revealed very few catecholamine-containing small vesicles with a few organelles, which reflected immature cells. No biochemical or imaging evidence of recurrence or metastasis were evident 1 year after the surgery. We conducted a literature search in the PubMed database. A total of 33 cases were collected. Our case had the second-highest 24-hour urinary dopamine excretion and was the first in which immunostaining for catecholamine synthase and electron microscopy were performed together. Histological findings in our case give a possible hypothesis that the mechanism underlying a dopamine-secreting pheochromocytoma is associated with immature catecholamine vesicles in which dopamine β-hydroxylase is localized, thus resulting in inhibited conversion from dopamine to norepinephrine. We also discuss the reasons for the lack of catecholamine excess symptoms, whether preoperative management of α-blockade is needed, and the association between the prognosis and genetic mutation, with an extensive literature review.

Salivary gland cancers (SGCs) are diagnosed using histopathological examination, which significantly contributes to their progression, including lymph node/distant metastasis or local recurrence. In the current World Health Organization (WHO) Classification of Head and Neck Tumors: Salivary Glands (5th edition), malignant and benign epithelial tumors are classified into 21 and 15 tumor types, respectively. All malignant tumors have the potential for lymph node/distant metastasis or local recurrence. In particular, mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), salivary duct carcinoma, salivary carcinoma, not otherwise specified (NOS, formerly known as adenocarcinoma, NOS), myoepithelial carcinoma, epithelial–myoepithelial carcinoma, and carcinoma ex pleomorphic adenoma (PA) are relatively prevalent. High-grade transformation is an important aspect of tumor progression in SGCs. MEC, AdCC, salivary carcinoma, and NOS have a distinct grading system; however, a universal histological grading system for SGCs has not yet been recommended. Conversely, PA is considered benign; nonetheless, it should be cautiously treated to avoid the development of metastasizing/recurrent PA. The aim of this review is to describe the current histopathological aspects of the prognostic factors for SGCs and discuss the genes or molecules used as diagnostic tools that might have treatment target potential in the future.

KIT (CD117, c-kit) is a receptor tyrosine kinase involved in the tumorigenesis of several neoplasms. KIT is expressed by the secretory cells of normal sweat glands. We studied the KIT expression and KIT mutational status in various benign and malignant tumors of eccrine and apocrine glands. We included a total of 108 cases comprising 10 benign and 6 malignant sweat gland tumors, and KIT expression was immunohistochemically detected (positive rate): 10 syringomas (0%), 8 poromas (25%), 20 mixed tumors (40%), 21 spiradenomas (43%), 1 cylindroma (0%), 5 hidradenomas (40%), 7 syringocystadenoma papilliferum cases (0%), 1 papillary hidradenoma (100%), 2 tubulopapillary hidradenomas (50%), 8 hidrocystomas (29%), 2 adenoid cystic carcinomas (100%), 5 porocarcinomas (20%), 6 apocrine carcinomas (33%), 10 extramammary Paget diseases (30%), 1 spiradenocarcinoma (100%), and 1 syringocystadenocarcinoma papilliferum (0%). Most KIT-positive cells were luminal cells, arising from glandular structures. We performed polymerase chain reaction–single-strand conformation polymorphism for detecting KIT mutational status. All cases showed no mutations at hot spots for KIT (exons 9, 11, 13, and 17). KIT mutation does not seem to be mechanism for KIT expression, but the expression may be from native sweat glands.

Aortic valve neocuspidization has shown satisfactory clinical outcomes; however, autologous pericardium durability is a concern for young patients. This study applied an autologous collagenous membrane (Biosheet^®), produced by in-body tissue architecture, to aortic valve neocuspidization and investigated its long-term outcome in a goat model. Moulds were embedded subcutaneously in 6 goats. After 2 months, Biosheets formed in the moulds. We performed aortic valve neocuspidization using a portion of the sheets with a thickness of 0.20–0.35 mm, measured by optical coherence tomography. Animals were subjected to echocardiography and histological evaluation at 6 months (n = 3) and 12 months (n = 3). As a control, the glutaraldehyde-treated autologous pericardium was used in 4 goats that were similarly evaluated at 12 months. All animals survived the scheduled period. At 6 months, Biosheets maintained valve function and showed a regeneration response: fusion to the annulus, cell infiltration to the leaflets and appearance of elastic fibres at the ventricular side. After 12 months, the regenerative structure had changed little without regression, and there was negligible calcification in the 1/9 leaflets. However, all cases had one leaflet tear, resulting in moderate-to-severe aortic regurgitation. In the pericardium group, three-fourths of the animals experienced moderate-to-severe aortic regurgitation with a high rate of calcification (9/12 leaflets). Biosheets may have regeneration potential and anti-calcification properties in contrast to autologous pericardium. However, in order to obtain reliable outcome, further improvements are required to strictly control and optimize its thickness, density and homogeneity.

Diagnoses reflect clear cell morphologies when tumor cells have clear cytoplasm in many organs, and the nature of such clear cells is typically identified. Colorectal tubular adenoma or adenocarcinoma, conversely, rarely show clear cells, the reason for which remains uncertain. We report 2 colon tumors with clear cell components (Case 1: adenoma; Case 2: adenocarcinoma) and investigate the nature of the clear cells. Case 1 was a 75-year-old man with a superficial elevated polyp detected in the rectum for whom endoscopic submucosal dissection was performed. Microscopically, 10% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming tubular structures accompanied by conventional tubular adenoma. Case 2 was a 58-year-old man with a pedunculated polyp found in his sigmoid colon for which polypectomy was performed. Microscopically, 90% of the tumor showed dysplastic columnar epithelium with clear cytoplasm forming fused glands or cribriform structures adjacent to the ordinal tubular adenocarcinoma. In both cases, clear and ordinary tumor cells were negative for CK7 and positive for CK20 and CDX2, consistent with findings of colorectal origin. Different results were found for CEA and CD10 staining. CEA was positive on the luminal side of the conventional area in contrast diffuse cytoplasmic staining of the clear cell area in both cases. CD10 was only positive for the clear cell component of case 2. The clear cell components were negative for Periodic acid-Schiff (PAS), Alcian blue, and mucicarmine staining and AFP immunohistochemistry. An ultrastructural examination found multiple cytoplasmic lipid-like vacuoles in the clear cell component that were predominantly negative for adipophilin by immunoelectron microscopy. We investigated tubular adenoma and tubular adenocarcinoma with clear cell components. The accompanying conventional tubular adenoma or adenocarcinoma cells helped us to evaluate the atypia of the clear cells. Diffuse cytoplasmic staining of CEA and CD10 suggested that the clear cell component might harbor malignant potential. We were unable to verify the well-known causes of clear cytoplasm, such as an accumulation of glycogen, lipid, or mucin and enteroblastic differentiation. The causes of clear cells in the colorectal region remain uncertain; however, possible explanations include autolysis and carbohydrate elution.