SARS-CoV-2 Testing of the Maxillary Sinus Immediately after COVID-19 Recovery.

We report the case of a 19-year-old woman with left orbital floor fracture after a motorcycle accident. She presented with headache and diplopia; computed tomography showed herniation of the inferior rectus muscle into the maxillary sinus with orbital floor fracture. She was admitted for observation of her concussion and tested positive for coronavirus disease 2019 (COVID-19) half a day after admission. Her COVID-19 symptoms were mild; the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antigen quantification test was below the standard value on the 10th day of hospitalization, and her isolation was lifted. She had diplopia with vertical eye motion disorder and underwent reconstruction of her orbital floor fracture on the 11th day. Although the orbital floor was connected to the maxillary sinus due to the orbital floor fracture, the presence and the viral load of SARS-CoV-2 in the maxillary sinus were unknown. The surgeons performed the operation while wearing N95 masks. A SARS-CoV-2 antigen quantification test and PCR test were performed on a sample from the maxillary sinus mucosa obtained through the orbital floor fracture before reconstruction of orbital floor with a titanium mesh implant; both were negative. To our knowledge, this is the first report of SARS-CoV-2 testing from the maxillary sinus immediately after COVID-19 recovery. We believe that the risk of SARS-CoV-2 infection from the maxillary sinus is small if the antigen test from the nasopharynx is negative.

Pseudoaneurysm and Arteriovenous Fistula in the Radial Artery after Cardiac Catheterization: A Case Report.

We report the case of a 71-year-old man who was experiencing a gradually worsening, dull pain and a cold sensation in his right hand. Three months earlier, he underwent a percutaneous coronary intervention for angina pectoris using a transradial approach in his right wrist and developed an arteriovenous fistula (AVF), a complication of percutaneous coronary intervention. Ultrasonography and computed tomography revealed a pseudoaneurysm and an AVF that were reducing the blood flow in his right hand. We observed that the pseudoaneurysm and the AVF were close to the bifurcation of the superficial palmar artery (SPA) and that the superficial palmar arch had radial artery superiority. Because we thought it was important to maintain the blood flow of the SPA branch, we excised the pseudoaneurysm, sutured the artery directly via microsurgery, and ligated the arteriovenous shunt. After the operation, the patient's symptoms were alleviated. Computed tomography showed that the blood flow in his right hand was improved and that his right SPA branch from the radial artery was directly fed to the index finger. Because the blood circulation in the hand is dual dominant but with many anatomical variations, we believe that it is important to preserve the blood flow of the SPA in postcatheterization pseudoaneurysm and AVF repair.

Lack of collagen α6(IV) chain in mice does not cause severe-to-profound hearing loss or cochlear malformation, a distinct phenotype from nonsyndromic hearing loss with COL4A6 missense mutation.

Congenital hearing loss affects 1 in every 1000 births, with genetic mutations contributing to more than 50% of all cases. X-linked nonsyndromic hereditary hearing loss is associated with six loci (DFNX1-6) and five genes. Recently, the missense mutation (c.1771G>A, p.Gly591Ser) in COL4A6, encoding the basement membrane (BM) collagen α6(IV) chain, was shown to be associated with X-linked congenital nonsyndromic hearing loss with cochlear malformation. However, the mechanism by which the COL4A6 mutation impacts hereditary hearing loss has not yet been elucidated. Herein, we investigated Col4a6 knockout (KO) effects on hearing function and cochlear formation in mice. Immunohistochemistry showed that the collagen α6(IV) chain was distributed throughout the mouse cochlea within subepithelial BMs underlying the interdental cells, inner sulcus cells, basilar membrane, outer sulcus cells, root cells, Reissner's membrane, and perivascular BMs in the spiral limbus, spiral ligament, and stria vascularis. However, the click-evoked auditory brainstem response analysis did not show significant changes in the hearing threshold of Col4a6 KO mice compared with wild-type (WT) mice with the same genetic background. In addition, the cochlear structures of Col4a6 KO mice did not exhibit morphological alterations, according to the results of high-resolution micro-computed tomography and histology. Hence, loss of Col4a6 gene expression in mice showed normal click ABR thresholds and normal cochlear formation, which differs from humans with the COL4A6 missense mutation c.1771G>A, p.Gly591Ser. Therefore, the deleterious effects in the auditory system caused by the missense mutation in COL4A6 are likely due to the dominant-negative effects of the α6(IV) chain and/or α5α6α5(IV) heterotrimer with an aberrant structure that would not occur in cases with loss of gene expression.

Intraosseous Ganglion Cyst of the Sternoclavicular Joint.

We report the case of a 63-year-old man who presented with a mass on the right clavicle near the sternoclavicular joint. He had received prior puncturing treatment, but relapsed each time. Magnetic resonance imaging revealed that the mass was a ganglion cyst, which appeared to be connected to the right clavicle. Excisional biopsy revealed that the cyst was an intraosseous ganglion cyst, and the cavity was connected to the sternoclavicular joint. The cavity was filled with an artificial bone graft after curettage to prevent fracture. Histological examination showed that the cyst wall had no lining cells and consisted of fibrous connective tissue. To the best our knowledge, this case is the first report of an intraosseous ganglion cyst of the sternoclavicular joint.

Collagen XVIII Deposition in the Basement Membrane Zone beneath the Newly Forming Epidermis during Wound Healing in Mice.

The basement membrane (BM) is composed of various extracellular molecules and regulates tissue regeneration and maintenance. Here, we demonstrate that collagen XVIII was spatiotemporally expressed in the BM during skin wound healing in a mouse excisional wound-splinting model. Re-epithelialization was detected at days 3 and 6 post-wounding. The ultrastructure of epidermal BM was discontinuous at day 3, whereas on day 6 a continuous BM was observed in the region proximal to the wound edge. Immunohistochemistry demonstrated that collagen XVIII was deposited in the BM zone beneath newly forming epidermis in day 3 and 6 wounds. Laminin-332, known to be the earliest BM component appearing in wounds, was colocalized with collagen XVIII in the epidermal BM zone at days 3 and 6. The deposition of α1(IV) collagen and nidogen-1 in the epidermal BM zone occurred later than that of collagen XVIII. We also observed the short isoform of collagen XVIII in the epidermal BM zone at day 3 post-wounding. Collectively, our results suggested that collagen XVIII plays a role in the formation of the dermal-epidermal junction during re-epithelialization, and that it is the short isoform that is involved in the early phase of re-epithelialization.

Type IV collagen α6 chain is a regulator of keratin 10 in keratinization of oral mucosal epithelium.

Keratinized mucosa is of fundamental importance to maintain healthy gingival tissue, and understanding the mechanisms of oral mucosa keratinization is crucial to successfully manage healthy gingiva. Previous studies have shown a strong involvement of the basement membrane in the proliferation and differentiation of epithelial cells. Therefore, first, to identify the keratinized mucosa-specific basement membrane components, immunohistochemical analysis for the six alpha chains of type IV collagen was performed in 8-week-old mice. No difference in the expression pattern of type IV collagen α1(IV) and α2(IV) chains was observed in the keratinized and non-keratinized mucosa. Interestingly, however, type IV collagen α5(IV) and α6(IV) chains specifically were strongly detected in the keratinized mucosa. To analyze the functional roles of the type IV collagen isoform α6(IV) in oral mucosa keratinization, we analyzed Col4a6-knockout mice. Epithelial developmental delay and low levels of KRT10 were observed in new-born Col4a6-knockout mice. Additionally, in vitro experiments with loss-of function analysis using human gingival epithelial cells confirmed the important role of α6(IV) chain in epithelial keratinization. These findings indicate that α112:α556 (IV) network, which is the only network that includes the α6(IV) chain, is one regulator of KRT10 expression in keratinization of oral mucosal epithelium.

Nodular pseudoangiomatous stromal hyperplasia of mammary stroma in a case showing rapid tumor growth.

Pseudoangiomatous stromal hyperplasia (PASH) is an uncommon benign breast disease that presents as a localized breast mass. Breast tissue affected by PASH is characterized by a dense, collagenous proliferation of mammary stroma, forming interanastomosing capillary-like spaces. The importance of this benign lesion lies in distinguishing it from low grade angiosarcoma. We report a case of a 38-year-old woman who presented with a rapidly growing breast tumor. She visited our hospital with a complaint of a painless right breast mass. Physical examination revealed a 3.6 x 2.2 cm, oval, elastic-firm, well-defined and easily movable mass. Mammograms revealed no discrete mass or calcifications. Sonographic examination revealed a 3.5 x 2.5 x 2.2 cm, oval, well-defined and homogenous hypoechoic mass without a cyst. A fine-needle aspiration sample of the breast mass showed some clusters of epithelial cells with small papillary structures and many scattered stromal cells with naked nuclei. Based on these findings, a provisional diagnosis of fibroadenoma was made and the patient was followed up. One year after the first visit, the mass enlarged rapidly and a follow-up mammogram revealed an 8.2 x 5.5 cm circumscribed mass without calcifications. Given the history of rapid growth of the mass, tumor excision was performed. The excised tumor was well demarcated and had a smooth external surface. Histologic examination revealed normal breast ducts and lobules, and specific proliferative epithelial changes were not seen. The lobular and duct structure of the breast parenchyma were separated by an increased amount of stroma. The fibrous stroma contained numerous anastomosing slit-like spaces. Isolated spindle cells appeared intermittently at the margins of the spaces resembled endothelial cells. Immunohistochemical staining showed that endothelial cells lining true blood vessels were positive for Factor VIII-related antigen, but the spindle cells were negative for Factor VIII. Pseudoangiomatous stromal hyperplasia was diagnosed.