Immunohistochemical Expression of Lymphatic Endothelial Markers in Blue Rubber Bleb Nevus Syndrome.

INTRODUCTION: Blue rubber bleb nevus syndrome (BRBNS) is an uncommon vascular anomaly characterized by multifocal cutaneous, visceral, and other soft tissue or solid organ venous malformations. We observed that BRBNS lesions express immunohistochemical markers of lymphatic differentiation. METHODS: BRBNS histopathologic specimens assessed at our institution during the past 27 years were reviewed. Slides from 19 BRBNS lesions were selected from 14 patients (9 cutaneous, 9 gastrointestinal, and 1 hepatic). We recorded the involved anatomical compartments and presence/absence of thrombi or vascular smooth muscle. Immunohistochemical endothelial expression of PROX1 (nuclear) and D2-40 (membranous/cytoplasmic) was evaluated semi-quantitatively. RESULTS: Endothelial PROX1 immunopositivity was noted in all specimens; the majority (89.5%) demonstrated staining in more than 10% of cells. D2-40 immunopositivity was present in one-third (33%) of cutaneous lesions and only 1 gastrointestinal lesion. CONCLUSION: Endothelial cells in BRBNS almost always express 1 or more immunohistochemical markers of lymphatic differentiation.

Large Malignant Testicular/Paratesticular Tumors in Adolescence: Assessment of Gross Tumor Size in a Vulnerable Age Group.

OBJECTIVE: We hypothesized that reticence to address a groin mass may result in late presentation of testicular/paratesticular malignancy in early puberty through adolescence. METHODS: Malignant testicular and paratesticular tumors (malignant germ cell tumors and rhabdomyosarcomas) diagnosed at our institution from 1994-2023 for patients aged 11-20 were included. Clinicopathologic features were recorded, and statistically analyzed. RESULTS: Eighty-five cases were identified. Patient ages ranged from 11 to 20 years (mean 17 years, median 16 years). The greatest tumor dimension ranged from 0.8 to 18.0 cm (mean 4.4 cm, median 3.5 cm). Ten tumors (11.8% of cases) were ≥10.0 cm. In the 11-13-year-old age group, 100% of tumors (3/3) were ≥10 cm. The proportion of tumors ≥10 cm was significantly higher in the 11-13-year-old age group than in either the 14-16-year-old (P<0.001) or 17-20-year-old (P<0.001) age groups. CONCLUSION: This adolescent cohort with malignant testicular and paratesticular tumors showed a high proportion (11.8%) of very large (≥10 cm) tumors. Although the reasons are unknown and likely multifactorial, this study suggests that adolescents, particularly the 11-13 year age group, are a vulnerable population.