[Imaging Features and Differential Diagnosis of Meningiomas and Their Mimics].

Meningiomas are the most common brain tumors, often in the form of extra-axial masses adhering to the dura mater. Although there are typical imaging findings, meningiomas have a wide variety of imaging findings, owing to their different histological subtypes. Thus, it can be difficult to differentiate meningiomas from other diseases that present with similar imaging findings. This section outlines mimickers for monitoring meningiomas that present with imaging findings similar to those of meningiomas. Diseases that form masses and require differentiation from meningiomas include schwannomas, solitary fibrous tumors, dural metastases, and histiocytosis. Diseases that primarily present as dural thickening and require differentiation from meningiomas include hypertrophic duralitis, fungal infections, and IG4-related diseases. Notably, in addition to the various pathologies that can mimic meningiomas, such as those listed above, there are also cases in which the diagnosis of meningioma is difficult because of additional modifications, such as metastasis or meningioma infarction.

Imaging Features of Uncommon Entities That Manifest with Torsion.

Torsion is the twisting of an object along the axis, and various structures (organs and tumors) in the body can twist. Torsion causes initial lymphatic and venous outflow obstruction, leading to congestive edema, enlargement, venous hemorrhagic infarction, and surrounding edema. It can also cause subsequent arterial obstruction depending on the degree of torsion, leading to ischemia, infarction, necrosis, gangrene, and surrounding inflammation. Therefore, in several cases of torsion, immediate surgical intervention is required to improve blood flow and prevent serious complications. Clinical manifestations of torsion are often nonspecific and can affect individuals of varying ages and sex. Imaging plays an important role in the early diagnosis and management of torsion. Multiple imaging modalities, including US, radiography, CT, and MRI, are used to evaluate torsion, and each modality has its specific characteristics. The imaging findings reflect the pathophysiologic mechanism: a twisted pedicle (whirlpool sign), enlargement of the torsed structures, reduced blood flow, internal heterogeneity, and surrounding reactive changes. The whirlpool sign is a definitive characteristic of torsion. In some cases, despite poor internal enhancement, capsular enhancement is observed on contrast-enhanced CT and MR images and is considered to be associated with preserved capsular arterial flow or capsular neovascularization due to inflammation. Radiologists should be familiar with the pathophysiologic mechanisms, clinical characteristics, and imaging characteristics of torsion in various structures in the body. Since other articles about common organ torsions already exist, the authors of this article focus on the uncommon entities that manifest with torsion. ©RSNA, 2024.

Unveiling the mille-feuille sign: a key to diagnosing ovarian carcinosarcoma in addition to ovarian metastasis from colorectal carcinoma on MRI.

PURPOSE: To clarify the diagnostic utility and formation of the Mille-feuille sign for ovarian carcinosarcoma (OCS) on MRI, and to evaluate the other MRI findings and serum markers compared to ovarian metastases from colorectal carcinoma (OMCRC). METHOD: Three blinded radiologists retrospectively reviewed MR images of 12 patients with OCS, 18 with OMCRC, and 40 with primary ovarian carcinoma (POC) identified by the electronic database of radiology reports. The interobserver agreement was analyzed using Fleiss' kappa test. Their MRI characteristics and tumor markers were compared using Fisher's exact test and Mann-Whitney's U test. Receiver operating characteristic curve analyses were used to determine the cutoff points for the ADC value. This study was approved by the institutional ethics committee. RESULTS: Interobserver agreement analysis was moderate or higher for all MRI characteristics. The frequency of Mille-feuille sign was comparable for both OCS and OMCRC groups, and predominantly higher than that of the POC group (p < 0.001, p < 0.001), respectively. Pathologically, the Mille-feuille sign in OCS reflected alternating layers of tumor cells with stroma and necrosis or intraluminal necrotic debris. Compared to OMCRC, intratumoral hemorrhage (p = 0.02), margin irregularity (p = 0.048), unilateral adnexal mass (p = 0.02), and low ADC values (p < 0.01) were more frequently observed and serum CEA levels was significantly lower (p = 0.007) in the OCS group. Under setting of the cutoff value of ADC at 0.871 × 10-3mm2/s, the discriminative ability for OCS showed 66.7% sensitivity, 94.4% specificity, and 81.0% accuracy, respectively. CONCLUSIONS: The Mille-feuille sign was seen in both OCS and OMCRC. MR findings of intratumoral hemorrhage, margin irregularity, unilateral adnexal mass, low ADC values, and low serum CEA levels can be useful in differentiating OCS from OMCRC.

A Case of Solid-Appearing Struma Ovarii: Pitfall in the Assessment Using Ovarian-Adnexal Reporting and Data System Magnetic Resonance Imaging Score.

Struma ovarii is a monodermal teratoma characterized by the presence of >50% thyroid tissue. It is mostly benign; therefore, preoperative diagnosis is important. It usually manifests as a multilocular cystic mass but rarely as a predominantly solid mass. On magnetic resonance imaging (MRI), solid-appearing struma ovarii showed early signal intensity enhancement on dynamic gadolinium-enhanced T1-weighted images, which histopathologically indicates the presence of thyroid tissue with abundant blood vessels. The Ovarian-Adnexal Reporting and Data System (O-RADS) MRI score is a validated classification worldwide for characterizing adnexal lesions. Based on the morphology, signal intensity, and enhancement of any solid tissue on the MRI, the scoring system can be used to classify adnexal lesions into five categories from score one (no adnexal mass) to score five (high risk of malignancy). An adnexal solid mass with a higher signal intensity than that of the myometrium 30-40 seconds after gadolinium (Gd) injection on non-dynamic contrast-enhanced (non-DCE) MRI was assigned a score of 5 (high risk of malignancy).  We present a case of solid-appearing struma ovarii with a higher signal intensity than that of the myometrium 30 seconds after Gd injection on non-DCE MRI, and it was classified as score five preoperatively. Therefore, a total abdominal hysterectomy with bilateral salpingo-oophorectomy was performed despite the presence of a benign ovarian mass. When an adnexal mass with a higher signal intensity than that of the myometrium 30-40 seconds after Gd injection on non-DCE MRI is encountered, struma ovarii should be included in the differential diagnosis, despite the O-RADS MRI score of five and management of the situation should be discussed.

Magnetic resonance imaging features of complete androgen insensitivity syndrome in comparison to Mayer-Rokitansky-Küster-Hauser syndrome.

PURPOSE: Complete androgen insensitivity syndrome (CAIS) and Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) share common clinical features such as female phenotype, vaginal hypoplasia, and primary amenorrhea. Magnetic resonance imaging (MRI) is performed to investigate the cause of primary amenorrhea. However, the MRI features are also similar in both disorders. They are ultimately diagnosed by chromosome testing, but there is a possibility of misdiagnosis if chromosome testing is not performed. This study aimed to identify MRI features that are useful for differentiating CAIS from MRKHS. METHOD: This multicenter retrospective study included 12 patients with CAIS and 19 patients with MRKHS. Three radiologists blindly evaluated the following features: (1) detection of vagina, (2) detection of nodular and cystic structures in the lateral pelvis; undescended testicles and paratesticular cysts in CAIS and rudimentary uteri and ovaries in MRKHS, (3) their location, (4) number of cysts in the cystic structures, and (5) signal intensity on diffusion-weighted images (DWI) and apparent diffusion coefficient (ADC) values of the nodular structures. Statistical comparisons were performed using Mann-Whitney U and Fisher's exact tests. RESULTS: Compared with MRKHS, the CAIS group showed significantly detectable vagina, more ventrally located nodular and cystic structures, fewer cysts within the cystic structures, and nodular structures with higher signal intensity on DWI and lower ADC values. CONCLUSIONS: MRI features of detectable vagina, location of nodular and cystic structures, number of cysts within the cystic structures, signal intensity on DWI and ADC values of the nodular structures were useful in differentiating CAIS from MRKHS.

Impact of CT-determined low kidney volume on renal function decline: a propensity score-matched analysis.

OBJECTIVES: To investigate the relationship between low kidney volume and subsequent estimated glomerular filtration rate (eGFR) decline in eGFR category G2 (60-89 mL/min/1.73 m2) population. METHODS: In this retrospective study, we evaluated 5531 individuals with eGFR category G2 who underwent medical checkups at our institution between November 2006 and October 2017. Exclusion criteria were absent for follow-up visit, missing data, prior renal surgery, current renal disease under treatment, large renal masses, and horseshoe kidney. We developed a 3D U-net-based automated system for renal volumetry on CT images. Participants were grouped by sex-specific kidney volume deviations set at mean minus one standard deviation. After 1:1 propensity score matching, we obtained 397 pairs of individuals in the low kidney volume (LKV) and control groups. The primary endpoint was progression of eGFR categories within 5 years, assessed using Cox regression analysis. RESULTS: This study included 3220 individuals (mean age, 60.0 ± 9.7 years; men, n = 2209). The kidney volume was 404.6 ± 67.1 and 376.8 ± 68.0 cm3 in men and women, respectively. The low kidney volume (LKV) cutoff was 337.5 and 308.8 cm3 for men and women, respectively. LKV was a significant risk factor for the endpoint with an adjusted hazard ratio of 1.64 (95% confidence interval: 1.09-2.45; p = 0.02). CONCLUSION: Low kidney volume may adversely affect subsequent eGFR maintenance; hence, the use of imaging metrics may help predict eGFR decline. CRITICAL RELEVANCE STATEMENT: Low kidney volume is a significant predictor of reduced kidney function over time; thus, kidney volume measurements could aid in early identification of individuals at risk for declining kidney health. KEY POINTS: • This study explores how kidney volume affects subsequent kidney function maintenance. • Low kidney volume was associated with estimated glomerular filtration rate decreases. • Low kidney volume is a prognostic indicator of estimated glomerular filtration rate decline.

Case Report: Tuberous sclerosis complex-associated hemihypertrophy successfully treated with mTOR inhibitor sirolimus.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder caused by a mutation in either of the two tumor suppressor genes, TSC1 and TSC2. Due to dysregulated activity of the mammalian target of rapamycin (mTOR) pathway, hamartomas or benign tumors frequently occur in many organs and are often treated with mTOR inhibitors. Hemihypertrophy is a rare complication of TSC. Although not being a tumor, progressive overgrowth of the affected limb may cause cosmetic and functional problems, for which the efficacy of mTOR inhibitors has not been reported previously. We herein report a case of TSC-associated hemihypertrophy. In this case, genetic studies revealed TSC1 loss of heterozygosity as the cause of hemihypertrophy. Clinically, pharmacological treatment with an mTOR inhibitor sirolimus successfully ameliorated cosmetic and functional problems with no intolerable adverse effects.

Choroid plexus and pituitary gland hemochromatosis induced by transfusional iron overload: Two case reports.

Hemochromatosis is a primary or secondary pathological condition characterized by the deposition of excess iron in the body tissues, which can eventually lead to cellular damage and organ dysfunction. Although excess iron deposition in the central nervous system is rare, involvement of the choroid plexus, pituitary gland, cortical surfaces, and basal ganglia has been reported to date. This case report describes 2 cases of transfusion-induced hemochromatosis involving the choroid plexus and pituitary gland, which were diagnosed by magnetic resonance imaging (MRI). In both cases, gradient echo (GRE) sequences, such as T2 star-weighted image and susceptibility-weighted imaging demonstrated markedly low signal intensity in the choroid plexus. Furthermore, the pituitary gland showed low signal intensity on T2-weighted images in Patient 2. Because these low signal intensities were not seen prior to red blood cell transfusion, they were diagnosed with transfusion-induced hemochromatosis. Brain MRI with GRE sequences was useful in detecting iron deposition in the choroid plexus. Considering that iron deposition in the body tissues can lead to irreversible organ damage, MRI with GRE sequences should be considered for patients with suspected iron overload.

Abscopal Effect after Stereotactic Body Radiotherapy with Nivolumab for Lung Metastasis of Head and Neck Cancer: A Case Report.

Introduction: The abscopal effect (AE) is a phenomenon, in which radiotherapy exerts an antitumour effect on distant lesions outside the primary irradiated area. Although immune checkpoint inhibitors have been widely studied for their potential to enhance the AE and improve patient outcomes, findings in cases of head and neck cancers remain limited. Case Presentation: We report the case of a 72-year-old man who experienced lung oligoprogression during nivolumab treatment for metastatic hypopharyngeal cancer. Stereotactic body radiotherapy (SBRT) was administered to one of the lung lesions, after which both irradiated and nonirradiated lesions regressed. Upon an 18-month follow-up period after SBRT, the patient showed no disease progression or toxicity, and continued receiving nivolumab therapy. Conclusion: The intent behind presenting this case report was to contribute to the accumulation of evidence regarding the AE in cases of head and neck cancer.

Efficient gene transduction in pigs and macaques with the engineered AAV vector AAV.GT5 for hemophilia B gene therapy.

Gene therapy using adeno-associated virus (AAV)-based vectors has become a realistic therapeutic option for hemophilia. We examined the potential of a novel engineered liver-tropic AAV3B-based vector, AAV.GT5, for hemophilia B gene therapy. In vitro transduction with AAV.GT5 in human hepatocytes was more than 100 times higher than with AAV-Spark100, another bioengineered vector used in a clinical trial. However, liver transduction following intravenous injection of these vectors was similar in mice with a humanized liver and in macaques. This discrepancy was due to the low recovery and short half-life of AAV.GT5 in blood, depending on the positive charge of the heparin-binding site in the capsid. Bypassing systemic clearance with the intra-hepatic vascular administration of AAV.GT5, but not AAV-Spark100, enhanced liver transduction in pigs and macaques. AAV.GT5 did not develop neutralizing antibodies (NAbs) in two of four animals, while AAV-Spark100 induced serotype-specific NAbs in all macaques tested (4 of 4). The NAbs produced after AAV-Spark100 administration were relatively serotype specific, and challenge with AAV.GT5 through the hepatic artery successfully boosted liver transduction in one animal previously administered AAV-Spark100. In summary, AAV.GT5 showed different vector kinetics and NAb induction compared with AAV-Spark100, and intra-hepatic vascular administration may minimize the vector dose required and vector dissemination.

Magnetic resonance imaging findings of sclerosing microcystic adenocarcinoma: A case report and review of the literature.

Sclerosing microcystic adenocarcinoma (SMA) is a rare malignant tumor of the salivary glands that closely resembles cutaneous microcystic adnexal carcinoma (MAC). It was newly listed in the 5th edition of the WHO classification of head and neck tumors. This report describes the case of a 61-year-old woman who presented with masses on the floor of the mouth. The masses showed low signal intensity on T2-weighted images (T2WI) and with low apparent diffusion coefficient (ADC) values. Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) revealed a plateau or persistence after rapid initial enhancement. Histopathologically, the tumors comprised small infiltrating strands of cells that formed small ducts and cysts embedded in thick fibrous stroma, consistent with SMA. Low signal intensity on T2WI with a low ADC value and a plateau or persistence after rapid initial enhancement on DCE-MRI reflect the fibrous and cellular components of the tumor and can be considered characteristic MRI findings of SMA.

Clinical Outcomes of Radiotherapy for Stage 1 Glottic Carcinoma: Comparing Accelerated Hyperfractionation and Once-daily Fractionation.

BACKGROUND/AIM: Accelerated hyperfractionation (AHF) is used in head and neck cancer to improve the local control (LC) rate, but reports of outcomes for early-stage GC are limited. The outcomes of radiotherapy (RT) for stage 1 glottic carcinoma (GC) were retrospectively analyzed, comparing AHF and once-daily fractionation (ODF) using 2.0-2.4 Gy. PATIENTS AND METHODS: A total of 102 patients with stage 1 GC underwent RT alone between 2007 and 2021, with 43 in the AHF group and 59 in the ODF group. A p-value less than 0.05 was considered to indicate a significant difference. RESULTS: The 5-year LC rate was 98% in the AHF group and 91% in the ODF group (p=0.19). During RT, significantly more patients in the AHF group required opioids due to mucositis than in the ODF group (74% vs. 25%, p<0.001), and the rate of aspiration pneumonia tended to be higher in the AHF group than in the ODF group (7% vs. 0%, p=0.072). CONCLUSION: There was no difference in the LC rate between AHF and ODF for stage 1 GC. Moreover, the AHF group required opioids at a higher rate and tended to have a higher risk of developing aspiration pneumonia.

Intradural Chordoma Mimicking an Epidermoid Cyst on Imaging.

Chordomas are rare, locally aggressive, primary bone tumors derived from primitive notochord remnants. They almost always arise within the axial skeleton, particularly in the skull base and the sacrococcygeal region. They usually present as extradural tumors, but rarely, they present as entirely intradural tumors. This report describes a case of intradural chordoma that mimicked an epidermoid cyst. A 72-year-old woman was incidentally found to have a prepontine extra-axial mass on magnetic resonance imaging. The mass gradually increased in size, and she felt discomfort in the right cheek area. The mass showed similar signal intensity to cerebrospinal fluid on T1-weighted images and T2-weighted images, but high signal intensity on fluid-attenuated inversion recovery images and diffusion-weighted images. Because the presence of very faint contrast enhancement was not noticed, the mass was preoperatively diagnosed as an epidermoid cyst. Tumor resection was performed, and the histopathological diagnosis was chondroid chordoma. Since intradural chordoma may resemble an epidermoid cyst on imaging, radiologists should check carefully for the presence of contrast enhancement and suggest the possibility of intradural chordoma.

Neurofilament light chain levels in cerebrospinal fluid as a sensitive biomarker for cerebral adrenoleukodystrophy.

OBJECTIVE: Adrenoleukodystrophy (ALD) has a poor prognosis when it progresses to the cerebral form (CALD). The aim of this study is to investigate whether cerebrospinal fluid (CSF) neurofilament light chain (cNfL) is a sensitive biomarker for detecting CALD and assessing response to hematopoietic stem cell transplantation (HSCT). METHODS: We conducted a cross-sectional study of 41 male ALD patients. The cNfL levels in patients with the cerebral form of ALD (CALD) or the cerebello-brainstem form of ALD were compared with those in patients with adrenomyeloneuropathy (AMN). The correlation between cNfL levels and MRI-based Loes severity scores was investigated. A longitudinal analysis was performed on patients who underwent multiple CSF examinations. RESULTS: The cNfL levels in 22 patients with CALD were significantly higher than those in 14 patients with AMN (median, 5545 vs. 1490 pg/mL; p < 0.001). The cutoff cNfL level of 1930 pg/mL showed good sensitivity (95.5%) and specificity (85.7%) for distinguishing CALD from AMN. The cNfL levels were positively correlated with Loes scores (p < 0.001). The cNfL levels in three AMN patients who later converted to CALD increased above the cutoff level during the conversion period, while the cNfL levels in four patients who remained in AMN were consistently below the cutoff. In 10 ALD patients who underwent HSCT, their cNfL levels decreased 3-24 months after HSCT. Two patients whose cNfL increased after HSCT showed deterioration in cognitive functions. INTERPRETATION: The cNfL level is useful for evaluating the disease activities of ALD and the response to HSCT.

Massive true thymic hyperplasia with osseous metaplasia.

True thymic hyperplasia is defined as an increase in both the size and weight of the gland, while maintaining a normal microscopic architecture. Massive true thymic hyperplasia is a rare type of hyperplasia that compresses adjacent structures and causes various symptoms. Limited reports address the imaging findings of massive true thymic hyperplasia. Herein, we report a case of massive true thymic hyperplasia in a 3-year-old girl with no remarkable medical history. Contrast-enhanced CT revealed an anterior mediastinal mass with a bilobed configuration containing punctate and linear calcifications in curvilinear septa, which corresponded to lamellar bone deposits in the interlobular septa. To our knowledge, this is the first report of massive true thymic hyperplasia with osseous metaplasia. We also discuss the imaging features and etiology of massive true thymic hyperplasia with osseous metaplasia.

Favorable outcome of hematopoietic stem cell transplantation in late-onset Krabbe disease.

BACKGROUND: Late-onset Krabbe disease is a disorder with autosomal recessive inheritance caused by a deficiency in galactocerebrosidase (GALC) activity. Its late-onset form usually shows slow disease progression with atypical symptoms including spastic paresis. The efficacy of hematopoietic stem cell transplantation (HSCT) in late-onset Krabbe disease has not been fully established. CASE REPORT: We describe the case of a patient with late-onset Krabbe disease showing progressive spastic paraparesis. At the age of 18, one and a half years after the development of symptoms, the patient underwent HSCT. After HSCT, the patient's GALC activity returned to a normal level and the lesions in the brain and spinal cord became faint on images. Over two and a half years after the HSCT, the patient's gait remained spastic, however, an improvement in gait speed and modified Rankin Scale score was observed. No severe adverse events occurred during this period. CONCLUSION: Our experience reported herein provides additional evidence for a favorable course in HSCT conducted in the early course of late-onset Krabbe disease.

Successful Preoperative QUAD SHOT for Bulky Parotid Carcinoma: Potential Preoperative Ultra-Hypofractionated Radiotherapy for Conversion Surgery.

QUAD SHOT is an ultra-hypofractionated radiotherapy (RT) technique that prescribes 14.0-14.8 Gy over 2 days. Although this technique has already gained some status as an effective palliative treatment for inoperable head and neck cancer (HNC), its application in other situations has not been given much consideration. Herein, we report a case of a 62-year-old woman who received preoperative QUAD SHOT therapy for poorly differentiated parotid carcinoma. In this case, after two courses of QUAD SHOT plus a standard chemotherapy regimen with pembrolizumab, the patient's inoperable, bulky tumor shrank dramatically and became operable. Best of all, while adequate therapeutic effects were achieved, the patient's time commitment and physical exertion were limited. RT during this period consisted of only eight fractions over 4 days. According to previous reports, the response rate for QUAD SHOT is sufficiently high, and the rate of serious adverse events is quite low. This case asks the question of whether the indications for QUAD SHOT irradiation can be expanded as one of the preoperative interventions undertaken by HNC surgeons to achieve conversion surgery.

A case of germinoma located in the fornix inducing transsynaptic atrophy of the Papez circuit.

Germinoma is a rare CNS germ cell tumor preferentially affecting children and young adults. Intracranial germinomas arise typically in the neurohypophysis and pineal region and occasionally in the basal ganglia and thalamus. Germinomas in the basal ganglia and thalamus are characterized by the ipsilateral cerebral and brainstem hemiatrophy with slowly progressive neurological deficits, which is due to tumor infiltration into the thalamocortical and corticospinal tract and induction of anterograde and retrograde Wallerian degeneration. We report an 11-year-old boy with a mass located in the fornix incidentally discovered on the first work-up of his minor head injury. Imaging findings revealed the ipsilateral atrophy of the mammillary body and the fornix. Stereotactic brain biopsy was performed and the final diagnosis was germinoma. The ipsilateral atrophy of the mammillary body and the fornix implied the transsynaptic degeneration via the Papez circuit. We discuss the unique nature of germinomas and underlying pathological mechanisms.

Magnetic Resonance Imaging Findings of Lymphoepithelial Carcinoma of the Submandibular Gland: A Case Report.

Lymphoepithelial carcinoma (LEC) is an uncommon neoplasm strongly associated with Epstein-Barr virus (EBV). LEC of the salivary glands (LECSG) is very rare: the most commonly affected site is the parotid gland, followed by the submandibular gland. This report describes the case of a 58-year-old man who presented with a left submandibular mass that had gradually increased in size over five years. On magnetic resonance imaging (MRI), the mass showed low apparent diffusion coefficient (ADC) values, rapid initial enhancement before reaching a plateau on dynamic contrast-enhanced MRI (DCE-MRI), and internal septal-like enhancement. Histopathologically, the tumor comprised polygonal or round tumor cells with atypical or pleomorphic nuclei and numerous lymphocytes, separated by heavy fibrosis. Immunohistological findings were positive for AE/AE3, CD20, and EBV-encoded small RNA in situ hybridization (EBER-ISH), consistent with LEC. A low ADC value with rapid initial enhancement before reaching a plateau on DCE-MRI was thought to reflect abundant cellular components with tumor neoangiogenesis, whereas internal septal-like enhancement reflects separating heavy fibrosis. To the best of our knowledge, this is the first case report describing ADC value and DCE-MRI findings of LECSG, and these findings can be considered characteristic MRI findings of LECSG.

Nintedanib-Induced Delayed Mucosal Healing after Adjuvant Radiation in a Case of Oropharyngeal Carcinoma.

Since the launch of imatinib in 2001, tyrosine kinase inhibitors are being used in chemotherapy for a wide range of malignant tumors. Drugs that inactivate multiple molecular mechanisms are called multikinase inhibitors (MKIs). Nintedanib is a type of MKI that inhibits downstream cascades in three systems: vascular endothelial growth factor receptor, fibroblast growth factor receptor, and platelet-derived growth factor receptor inhibitions. It was initially developed as an anticancer drug for non-small-cell lung carcinoma; however, it was also found to inhibit the proliferation of fibroblasts associated with chronic inflammation in the lungs. Therefore, it is being more widely used to treat idiopathic pulmonary fibrosis, a benign disease, than as an antineoplastic agent. Several studies have reported adverse events associated with the concurrent use of MKIs with surgery or radiotherapy. Specifically, there has been a report cautioning against delayed wound healing associated with the use of nintedanib in patients undergoing surgery. However, there is no specific mention of its concurrent use during irradiation. We describe a case of a 72-year-old man with severely delayed recovery from radiation mucositis when nintedanib was being administered for benign disease.