UNASSIGNED: Titanium dioxide is a versatile compound that is found in a variety of consumer products, medical hardware, and pharmaceuticals. Although oral and topical ingestion of this compound is common, intravenous introduction is much less common. We present three cases where significant titanium dioxide deposits were identified in liver and splenic tissue of three decedents, all of whom died of illicit drug overdose in the same geographic area and had fentanyl and its metabolites in blood on postmortem toxicologic testing. At autopsy, liver sections had a granular texture with fine white stippling grossly, and histologic examination of hepatic and splenic tissues showed scattered patches of black granular material with pink birefringence. Energy-dispersive x-ray spectroscopy performed on these tissues revealed the presences of clusters of titanium dioxide. Immunohistochemical staining of both the liver and spleen with CD68 confirmed the titanium dioxide clusters were within macrophages. Intravenous titanium dioxide nanoparticle elimination studies in rats suggest a time sensitive period for this elimination, with a transient period of pigment deposition between 1-58 days following injection. If a time-dependent link between titanium dioxide pigment deposition within tissues and intravenous drug use can be shown, this could be a valuable tool for Pathologists.

报道多系统受累的间变性淋巴瘤激酶（ALK）阳性组织细胞增生症1例。患者女，35岁。因发现左乳肿物10 d入院。镜下见乳腺组织内梭形细胞增生、交错排列，细胞核卵圆形，核分裂象罕见，胞质丰富、嗜碱或透亮，背景可见散在淋巴细胞浸润，及散在残存的脂肪细胞及乳腺导管。免疫组织化学染色显示异常增生的梭形细胞CD68、CD163、ALK阳性，广谱细胞角蛋白（CKpan）、p63、Langerin、S-100蛋白、CD34、β-catenin、结蛋白、Calponin、STAT6阴性。ALK荧光原位杂交（FISH）分离探针检测显示ALK基因有断裂。二代测序于DNA及RNA水平均检测到ALK：：KIF5B基因融合。ALK阳性组织细胞增生症是新近收录于第5版WHO造血与淋巴组织肿瘤的罕见病例，是伴有ALK：：KIF5B基因融合的独特亚型，常常伴有多系统受累，ALK抑制剂靶向治疗有效、但远期生存情况不明确。经验不足的医师容易因认识不足而误诊，因此需要充分认识其临床表现、病理特征与分子改变。.

BACKGROUND:  Intracranial aneurysms are more commonly associated with inflammation as a cause of their development, progression, and rupture. Macrophages and other cells can express the CD68 antigen. The aim of this study was to assess the CD68 antigen levels in cerebral aneurysm (CA) patients compared to a control group at a referral center in Iran.
METHODS:  A case-control investigation was undertaken on 88 individuals (44 of whom were cases and 44 were controls). Individuals with CA as the case group consisted of 28 ruptured and 16 unruptured subgroups. Clinical, radiographic, and CD68 levels were evaluated and registered.
RESULTS:  The average age of the participants was 49 years. Males comprised 43.2% of the patients, while 56.8% were females (p = 0.002). There was a statistically significant difference in the CD68 levels between the two groups. There was no significant difference (p = 0.42) between the ruptured and unruptured subgroups (23.66 and 20.47, respectively) in this comparison. No significant correlation was seen between the patients\' CD68 and Glasgow Coma Scale (GCS) levels and their aneurysm diameter (p = 0.74 and 0.45, respectively). A link between CD68 levels and age was found, but it was not statistically significant (r = 0.44 and p = 0.002).
CONCLUSIONS:  A possible involvement of CD68 as an inflammatory agent in the development of CAs but not in aneurysm rupture has been suggested. Inflammation and CD68 were positively associated with age. The CD68 antigen should be studied further in population-based cohort studies.