Recurrent Zenker's Traction Diverticulum After Cervical Spine Surgery: Lessons Learned.

This is a report of our institutional experience regarding pharyngoesophageal diverticula formation following anterior cervical spine surgery (ACSS). It is a retrospective chart review of institutional patients from January 2008 to May 2020. Patients at our institution were identified by our two senior authors. Inclusion criteria included patients > 18 years old, a history of prior ACSS, and a confirmed diagnosis of pharyngoesophageal diverticulum with radiographic imaging. Three patients were identified to have an ACSS-related diverticulum. The case presentations describe surgical management and the subsequent postoperative course. One patient had a particularly complicated course with recurrent diverticulum formation despite prior excision. The patient continued to have dense scar tissue adhering the posterior esophageal wall to the nearby cervical spine plates, despite prior excision and rotation of nearby tissue. This difficult case demonstrated the need for an open and aggressive approach. ACSS-related diverticula that form in patients with a history of prior anterior cervical spine surgery appear to be a form of traction diverticulum due to dense scar tissue that adheres the pharyngoesophageal mucosa to the adjacent cervical spinal plate. This type of diverticulum differs from Zenker's diverticulum. Surgical management is recommended to resolve patients' symptoms.

Microvascular reconstruction of medication related osteonecrosis of the head and neck.

BACKGROUND: Medication related osteonecrosis of the jaw (MRONJ) requiring free flap (FF) reconstruction is uncommon with limited reported findings. METHODS: Multicenter, retrospective case series of 49 consecutive adult patients presenting with advanced MRONJ requiring FF reconstruction from 2010 to 2022. Perioperative complications and outcomes were analyzed. RESULTS: Eighty-two percent (n = 40) of cases were of the mandible and 18% (n = 9) were of the maxilla. The mean follow-up was 15 months (±19.6). The majority of FF survived (96%, n = 47). FF reconstructions of the maxilla were more likely to require postoperative debridement (56%, 95% CI [27, 81%] vs. 15%, 95% CI [7, 25%], p = 0.008) or develop intraoral bone exposure (56%, 95% CI [27, 81%] vs. 18%, 95% CI [9, 27%], p = 0.02). Most patients (71%, n = 35) received preoperative antibiotics which was associated with a higher rate of FF survival (100% vs. 86%, 95% CI [60, 96%], p = 0.02) and fewer complications. CONCLUSIONS: Patients undergoing FF reconstruction for MRONJ do well with high rates of FF success. MRONJ of the maxilla have a higher rate of some complications. Preoperative antibiotics correlated with higher FF survival and fewer postoperative complications.

Microvascular Free Flap Outcomes in Maxillectomy Defects from Invasive Fungal Sinusitis.

OBJECTIVES: Microvascular free tissue transfer is routinely used for reconstructing midface defects in patients with malignancy, however, studies regarding reconstructive outcomes in invasive fungal sinusitis (IFS) are lacking. We aim to describe outcomes of free flap reconstruction for IFS defects, determine the optimal time to perform reconstruction, and if anti-fungal medications or other risk factors of an immunocompromised patient population affect reconstructive outcomes. METHODS: Retrospective review of reconstruction for IFS (2010-2022). Age, BMI, hemoglobin A1c, number of surgical debridements, and interval from the last debridement to reconstruction were compared between patients with delayed wound healing versus those without. Predictor variables for delayed wound healing and the effect of time on free flap reconstruction were analyzed. RESULTS: Twenty-seven patients underwent free flap reconstruction for IFS. Three patients were immunocompromised from leukemia and 21 had diabetes mellitus (DM). Patients underwent an average of four surgical debridements for treatment of IFS. The interval from the last IFS debridement to flap reconstruction was 5.58 months (±5.5). Seven flaps (25.9%) had delayed wound healing. A shorter interval of less than 2 months between the last debridement for IFS and reconstructive free flap procedure was associated with delayed wound healing (Fisher Exact Test p = 0.0062). Other factors including DM, BMI, HgA1c, and bone reconstruction were not associated with delayed wound healing. CONCLUSION: Patients with maxillectomy defects from IFS can undergo microvascular-free flap reconstruction with good outcomes while on anti-fungal medication. Early reconstruction in the first 2 months after the last IFS debridement is associated with delayed wound healing. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:1642-1647, 2024.

Outcomes Following Treatment for Carotid Blowout in Head and Neck Cancer Patients.

OBJECTIVE: The aim of the study was to determine outcomes after interventional radiology treatment of carotid blowout. METHODS: Patients with head and neck cancer and who received interventional radiology treatment for carotid blowout between 2000 and 2022 were included. Pre-treatment, treatment, and post-treatment variables were evaluated. RESULTS: Fourteen patients met inclusion criteria. Eleven patients (78.6%) had a history of radiation. Twelve (85.7%) blowouts occurred within 6 months of recent intervention. Initial treatment was with stenting (n = 9, 64.3%), coil embolization (n = 4, 28.6%), or both (n = 1, 7.1%). Six patients (42.9%) underwent subsequent carotid bypass. Morbidity following treatment included stroke (n = 1) and rebleeding (n = 4). Six-month survival was 57.1%. Of the patients who survived past six months, 5/8 were treated with carotid bypass and coverage. Four patients died of cancer progression, three of rebleeding, and three of medical complications. CONCLUSION: The majority of carotid blowout occurs within 6 months of surgery or radiation. Many who survive will die of cancer progression or medical illness. Carotid bypass with flap coverage may be a worthwhile treatment for carotid blowout and should be considered as an adjunct to endovascular treatment. LEVEL OF EVIDENCE: 4 Laryngoscope, 134:695-700, 2024.

Free Flap Outcomes for Head and Neck Surgery in Patients with COVID-19.

INTRODUCTION: Coronavirus disease 2019 (COVID-19) affects the vascular system, subjecting patients to a hypercoagulable state. This is of particular concern for the success of microvascular free flap reconstruction. This study aims to report head and neck free flap complications in patients with COVID-19 during the perioperative period. We believe these patients are more likely to experience flap complications given the hypercoagulable state. METHODS: This is a multi-institutional retrospective case series of patients infected with COVID-19 during the perioperative period for head and neck free flap reconstruction from March 2020 to January 2022. RESULTS: Data was collected on 40 patients from 14 institutions. Twenty-one patients (52.5%) had a positive COVID-19 test within 10 days before surgery and 7 days after surgery. The remaining patients had a positive test earlier than 10 days before surgery. A positive test caused a delay in surgery for 16 patients (40.0%) with an average delay of 44.7 days (9-198 days). Two free flap complications (5.0%) occurred with no free flap deaths. Four patients (10.0%) had surgical complications and 10 patients had medical complications (25.0%). Five patients (12.5%) suffered from postoperative COVID-19 pneumonia. Three deaths were COVID-19-related and one from cancer recurrence during the study period. CONCLUSION: Despite the heightened risk of coagulopathy in COVID-19 patients, head and neck free flap reconstructions in patients with COVID-19 are not at higher risk for free flap complications. However, these patients are at increased risk of medical complications. LEVEL OF EVIDENCE: 4 Laryngoscope, 2023.

A Rare Manifestation of Infectious Mononucleosis Tonsillitis.

The purpose of this case report is to describe a rare case of infectious mononucleosis (IM) hemorrhagic tonsillitis. Our patient presented with acute tonsillitis complicated by spontaneous tonsillar hemorrhage. This is a single case report with a literature review. A 19-year-old male presented to the emergency department with a 10-day history of worsening sore throat, recurrent fevers, malaise, and dysphagia to solids and liquids, as well as a three-day history of epistaxis and hemoptysis. He tested positive for Epstein-Barr virus and rhinovirus. On exam, a "hot potato" voice was noted along with bilateral tonsillar edema, erythema, and hypertrophy. Both tonsils with dry blood coating and no exudates were visualized. Computed tomography (CT) imaging of the neck demonstrated subcutaneous emphysema isolated to the tonsils. Treatment consisted of intravenous antibiotics and steroids, followed by an oral antibiotic, with subsequent full resolution of symptoms. This case illustrates a rare, severe manifestation of IM tonsillitis that radiographically can mimic other more severe soft-tissue neck infections on imaging, such as cervical necrotizing fasciitis. In patients presenting with hematemesis, hemoptysis, and/or epistaxis, along with tonsillar edema, erythema, and hypertrophy, a diagnosis of spontaneous hemorrhagic tonsillitis should be considered. The radiographic findings of soft-tissue emphysema in the deep spaces of the head and neck region may be seen in the setting of IM, mimicking other soft-tissue infections of the deep neck spaces.

Management of the Failing Flap.

Free tissue transfer has become the reconstructive modality of choice for replacing composite tissue defects. While the success rate in high-volume centers is reported to be greater than 95%, up to 10% of patients will require revision of their vascular anastomosis secondary to thrombosis or compromise to flow. In the intraoperative setting, immediate revision is successful in the majority of cases. Rarely, the flap cannot be revascularized and a secondary option must be used. In the perioperative setting revision is successful if the patient can be brought back to the operating room in a timely fashion. Revision rates up to 70% are reported. A small number of these patients may then suffer a second episode of compromise where revision is less successful at 30%. In these cases, consideration should be given to secondary reconstruction rather than attempting salvage. Finally, there are a small number of patients whose flaps will fail following discharge from the hospital. These patients can rarely be salvaged and secondary reconstructive options should be explored.

The Dynamic Tracheoesophageal Prosthesis Length.

OBJECTIVE: In a postlaryngectomy patient, tracheoesophageal (TE) speech is considered to be the most effective and preferred method of communication. Previous research has demonstrated that despite an appropriately sized TE prosthesis placement at the time of puncture, there are a portion of patients that require resizing postoperatively. The purpose of this study was to report on the variability of the tracheoesophageal prosthesis length. STUDY DESIGN: Retrospective chart review. SETTING: Tertiary care academic medical center. METHODS: This was a retrospective chart review of 62 patients who underwent secondary tracheoesophageal puncture (TEP) at a tertiary care academic medical center from January 2008 to November 2019. Patient demographic information, average changes in prosthesis length, number of prosthesis adjustments, and timing of prosthesis exchanges were collected. RESULTS: 62 patients met criteria for study inclusion. Mean age was 61.96 years old with 49 being male (79%) and 13 (21%) females. Overall change in prosthesis length was - 3.85 mm ± 3.58 with time to first prosthesis change at 2.29 months ± 2.73. There was an average of 4.37 changes ± 3.43 before reaching a stable length. Twenty-six patients (41.9%) had increases in their prosthesis length resulting in closure of the tracheoesophageal fistula requiring seven patients (11.3%) to return to the operating room for repuncturing. History of smoking (P = 0.02), Blom-Singer prosthesis type (P = 0.03), and larger diameter (P = 0.01) appeared to be predisposing factors for a fluctuating prosthesis length. CONCLUSION: Tracheoesophageal prosthesis length decreases over time for secondary punctures, requiring adjustments with a speech language pathologist. There are a clinically significant portion that have fluctuations in prosthesis length resulting in an increased risk for requiring re-puncturing.

Head and neck cancer readmission reduction (HANCARRE) project: Reducing 30-day readmissions.

Objective: Unplanned 30-day readmissions result in increased costs and decreased patient satisfaction. The objective of this study was to compare readmission rates before and after a multidisciplinary quality improvement initiative that focuses on patient and staff education, use of targeted skilled nursing facilities, and appropriate use of patient observation status. Methods: This was a quality improvement study of all unplanned admissions to the Head and Neck Oncology service at a tertiary care facility during a 3-year period between October 2015 and September 2018. In October 2016, when the Head and Neck Oncology service revised its discharge practices for patients undergoing extirpative and/or reconstructive surgery. These changes included enhancing patient education, increasing the use of a skilled nursing facility with directed staff education and patient handoffs by advanced practice nurses, and appropriate utilization of 23-h observation status for returning patients. The readmission rate from the pre-intervention era (October 2015 through September 2016) was compared to the readmission rate from the post-intervention era (October 2016 through September 2018). Secondary outcomes were the rates of 23-h observation within 30 days of the discharge as well as emergency room visits within 30 days of discharge. Results: In this sample of 449 patients, 161 (35.9%) were observed before the change-in-practice (before October 2016), and 288 (64.1%) were observed following the change-in-practice (after September 2016). On univariable analysis, the risk of readmission declined by approximately 41.4% from the pre-intervention era, though this conclusion was not statistically significant (P = 0.06). On multivariable analysis, patients at moderate or high risk of death were 2.31 times more likely than those at minor risk of death to readmit within 30 days (P = 0.03). Similarly, those with recurrent or persistent cancer were 3.33 times more likely than those undergoing initial curative surgical management of cancer to readmit within 30 days (P = 0.001). No patient characteristics were associated with a 23-h observation following discharge (all P > 0.05). Conclusions were similar for emergency room visits following discharge. Conclusions: A three-part quality improvement strategy resulted in a clinically important decrease in 30-day readmissions, though the decline was not statistically significant. There were no significant changes in 23-h observation within 30 days of discharge or emergency room visits within 30 days of discharge.

MR angiographic findings of aberrant right subclavian artery with agenesis of the left common carotid artery and anomalous origin of the vertebral arteries.

INTRODUCTION: Congenital aortic arch anomalies and variants have been extensively characterized in the medical literature. Proper identification of these anomalies is important when surgical or percutaneous interventions are indicated. CASE PRESENTATION: We present a case of a 48-year old male who presented to the emergency department with altered mental status. Magnetic resonance angiography (MRA) findings revealed an aberrant right subclavian artery (ARSA), early bifurcation of the right common carotid artery (CCA) with anomalous origin of the right vertebral artery (VA) from the right common carotid artery bifurcation, anomalous left vertebral artery originating from the aortic arch, and absent left common carotid artery with independent origins of the left external carotid artery (ECA) and internal carotid artery (ICA). No other abnormalities were identified, and the patient demonstrated no symptoms attributable to his vascular anomalies. CONCLUSION: To our knowledge, this unique combination of anomalies has never been reported in the literature. With an understanding of embryological pathways, even exceedingly rare anomalies like this one can be explained.

Sinusitis as a cause of insidious headache in a pregnant woman: A case report.

BACKGROUND: The incidence of headaches during pregnancy is 35%. Although ruling out pre-eclampsia as a possible cause for headache is important in the pregnant population, acute sinusitis should remain on the differential as it occurs six times more frequently in pregnant women. Untreated disease can lead to rare intracranial complications such as a subdural empyema.Case presentation: 21-year-old female with recurring headaches at 33 weeks of gestation was diagnosed with pre-eclampsia with severe features requiring emergent caesarean section. The woman continued to have altered mental status and focal neurologic deficits after delivery. Computerized tomography head imaging demonstrated a subdural collection discovered to be an empyema due to unilateral acute sinusitis of odontogenic origin. CONCLUSION: Maintaining a clinical suspicion for acute sinusitis as a cause of headache in a pregnant woman is important for prompt diagnosis and treatment before it develops into a rare intracranial complication.

Esophageal stenosis in head and neck cancer patients: Imaging's accuracy to predict dilation response.

OBJECTIVES: The primary goal of this study was to examine how well findings of cervical esophageal stenosis on modified barium swallow (MBS) and esophagram correlate with clinical improvement following dilation in patients with a history of head and neck (H&N) cancer. METHODS: A retrospective review was performed at an academic hospital. The study population included H&N cancer patients with a history of neck dissection surgery who underwent esophageal dilation from 2010 to2018. Pre and postdilation swallowing function was assessed. The Functional Outcomes Swallowing Scale (FOSS) and Functional Oral Intake Scale (FOIS) were used as outcome measures. RESULTS: The 95 patients were included. All patients had imaging prior to dilation. Post-dilation FOSS and FOIS scores were significantly improved (P < .001). In identifying the patients that would have improvement from dilation, esophagram and MBS had average sensitivities of 81% and 82%, respectively. The negative predictive value (ie, the ability of a normal esophagram or normal MBS to exclude patients that would not improve with dilation) was only 46% and 38%, respectively. When the specific finding of aspiration on MBS was considered, the positive predictive value (PPV) (ie, the ability of an MBS positive for aspiration to predict that a patient would benefit from dilation) was 87% (P = .03). When only the specific finding of stenosis on esophagram was considered, the PPV of improvement post-dilation was 58% (P = .97). The delay in time from imaging to dilation was significantly longer in those who had an unidentified stenosis (false negative) on imaging when compared to those who did not (46.8 ± 35.2 days vs 312.6 ± 244.1 days, P < .001). CONCLUSION: In high risk patients for cervical esophageal stenosis, such as those with a history of H&N cancer and open neck surgery with or without radiation, MBS and esophagram appear to have mixed reliability as predictors of response to esophageal dilation. In these patients, a "negative" result on MBS and esophagram may not be diagnostically accurate enough to exclude patients from consideration of dilation. LEVEL OF EVIDENCE: IIb.

Superior Semicircular Canal Dehiscence Syndrome Following Head Trauma: A Multi-institutional Review.

OBJECTIVE: To evaluate patients who become symptomatic from superior semicircular canal dehiscence (SSCD) following head trauma. STUDY DESIGN: Case series assessing patients presenting with SSCD after a trauma. METHODS: A case series was completed assessing patients presenting with SSCD after trauma. Data from three academic medical centers were evaluated, including the following: imaging, videonystagmography (VNG)/vestibular evoked myogenic potential (VEMP) testing, audiometric assessment, and surgical repair. Outcome measures included the following: 1) Description of audio-vestibular symptoms, 2) mean pre- and post-operative pure tone average (PTA), word recognition score (WRS), and air bone gap (ABG). RESULTS: A total of 14 patients were included; 86% were male. Approximately 43% were found to have bilateral SSCD on imaging, with 57% of patients pursuing surgical management. The most common presenting symptoms included pulsatile tinnitus (93%), autophony (79%), and hearing loss (64%). Approximately 36% of patients underwent VNG/VEMP testing, with 83.3% of those demonstrating abnormal results. The mean audiometric findings on the symptomatic side included an air-conduction PTA of 38.0 dB, bone-conduction PTA of 24.3 dB, WRS of 81%, and ABG of 17.9 dB. Among patients who underwent surgery (57%), there was no significant change in the air-conduction PTA, bone-conduction PTA, or WRS (P > .05). However, there was an improvement in the ABG (preoperative = 22.8 dB versus postoperative = 9.7 dB; P = .005). CONCLUSION: Head trauma may be a potentiating event for SSCD syndrome. This study advances the hypothesis that these patients likely have underlying radiographic SSCD prior to their trauma, and a traumatic event increases in intra-vestibular or intracranial pressures, unmasking SSCD syndrome. LEVEL OF EVIDENCE: 4 Laryngoscope, 131:E2810-E2818, 2021.

Cutaneous Vasculitis in a Patient With COVID-19.

We describe a 43-year-old patient with coronavirus disease 2019 who developed a bullous hemorrhagic rash that progressed to necrotic lesions. Histopathology confirmed a vasculitis of small- and medium-sized cutaneous vessels.

Total thyroidectomy: Safe and curative treatment option for hyperthyroidism.

BACKGROUND: While use of total thyroidectomy has increased in management of hyperthyroidism, concerns exist about increased surgical complication rates; most notably, hematoma, recurrent laryngeal nerve (RLN) injury, and hypocalcemia. METHODS: Retrospective cohort study of 454 patients undergoing total thyroidectomy between 2003 and 2015. All patients had surgery for hyperthyroidism, benign euthyroid disease, or thyroid malignancy. RESULTS: Total thyroidectomy for hyperthyroidism was not associated with an increased risk for any postoperative complication. Transient hypocalcemia, temporary dysphonia, and postoperative hematoma rates were not significantly different for patients with hyperthyroid (n = 91), euthyroid benign (n = 237), and malignant (n = 126) disease. Permanent hypocalcemia and recurrent laryngeal nerve injury were not noted in any hyperthyroid patients. Complication rates were similar for hyperthyroid patients with Graves' disease vs toxic multinodular goiter. CONCLUSION: This study affirms safety and efficacy of total thyroidectomy as standard treatment for hyperthyroidism.

Self-Resolving Vulvar Breast Tissue Arising in the Post-Partum Setting: A Case Report and Review of Literature.

INTRODUCTION: During the postpartum period, breast engorgement in preparation for lactation may trigger the onset of vulvar labial nodules that present with pain and discomfort. These labial nodules may originate from ectopic breast tissue and can rarely present in women during the postpartum period in the labia majora. MAIN ISSUE: A 37-year-old African American female, gravida 1 para 1, presented to the Loma Linda University Medical Center with complaints of new onset labial swelling worsening 6 days following her full term spontaneous vaginal delivery. Additionally, our respondent complained of difficulty breastfeeding due to intermittent lack of milk production. She reported bilateral breast engorgement with tenderness, despite frequent attempts at breastfeeding. The respondent's presentation did not meet the criteria for other common differentials due to the physical characteristics of the nodules. The location of the nodules along the milk line led physicians to believe that the respondent was presenting with engorged extra-mammary breast tissue in the labia majora. MANAGEMENT: The participant was told to observe her course over the next few days as she began to have milk production and ejection. The respondent was seen in clinic for her 6-week postpartum visit, and was no longer complaining of difficulty with breastfeeding. The labial nodules had resolved spontaneously. CONCLUSION: A literature search yielded no case reports that described a case of an extra-mammary vulvar mass that self-resolved with resolution of breast engorgement. The infrequent presentation of extra-mammary vulvar tissue makes it difficult to conclude a guideline for diagnosis and management.

Discharge breastmilk feeding rates in asymptomatic term newborns admitted to the neonatal intensive care unit for maternal chorioamnionitis.

PURPOSE: To compare discharge breastmilk feeding rates among asymptomatic term newborns receiving 48-hour versus >48-hour antibiotics in the neonatal intensive care unit (NICU) and a cohort of well-baby nursery (WBN) newborns. MATERIALS AND METHODS: This retrospective review included asymptomatic term neonates admitted to the NICU due to maternal chorioamnionitis and a comparison group of WBN neonates between January 2012 and December 2015. Demographic, birth, feeding, and lactation consultant visit data were analyzed in univariate and multivariate models. RESULTS: Among 272 NICU neonates, 237 (87%) received 48-hour antibiotics versus 35 (13%) who received >48-hour (h) antibiotics; a cohort of 428 WBN neonates was studied for comparison. Exclusive breastmilk feeding was seen in 14% of NICU versus 35% of WBN neonates (p < .01). Among NICU newborns, 48 h versus >48 h antibiotics was not associated with altered discharge breastmilk feeding (14 versus 14%; p = .89). On multivariate logistic regression analysis among NICU subjects, older maternal age (p < .01), lower parity (p = .02), first-feed breastmilk (p < .01), and more lactation consultant visits (p = .012) were associated with increased discharge breastmilk feeding. CONCLUSIONS: NICU admission for presumed early-onset sepsis due to maternal chorioamnionitis was associated with reduced discharge breastmilk feeding in asymptomatic term neonates, but prolonged antibiotic exposure was not. We speculate that demographic factors, such as maternal age and parity, may aid in focusing lactation consultant efforts to potentially improve NICU exclusive discharge breastmilk feeding rates.

Development and Characterization of A Novel Prox1-EGFP Lymphatic and Schlemm's Canal Reporter Rat.

The lymphatic system plays a key role in tissue fluid homeostasis, immune cell trafficking, and fat absorption. We previously reported a bacterial artificial chromosome (BAC)-based lymphatic reporter mouse, where EGFP is expressed under the regulation of the Prox1 promoter. This reporter line has been widely used to conveniently visualize lymphatic vessels and other Prox1-expressing tissues such as Schlemm's canal. However, mice have a number of experimental limitations due to small body size. By comparison, laboratory rats are larger in size and more closely model the metabolic, physiological, and surgical aspects of humans. Here, we report development of a novel lymphatic reporter rat using the mouse Prox1-EGFP BAC. Despite the species mismatch, the mouse Prox1-EGFP BAC enabled a reliable expression of EGFP in Prox1-expressing cells of the transgenic rats and allowed a convenient visualization of all lymphatic vessels, including those in the central nervous system, and Schlemm's canal. To demonstrate the utility of this new reporter rat, we studied the contractile properties and valvular functions of mesenteric lymphatics, developed a surgical model for vascularized lymph node transplantation, and confirmed Prox1 expression in venous valves. Together, Prox1-EGFP rat model will contribute to the advancement of lymphatic research as a valuable experimental resource.

The "don't eat me" signal CD47 is a novel diagnostic biomarker and potential therapeutic target for diffuse malignant mesothelioma.

Diffuse malignant mesothelioma (DMM) is one of the prognostically most discouraging cancers with median survivals of only 12-22 months. Due to its insidious onset and delayed detection, DMM is often at an advanced stage at diagnosis and is considered incurable. Combined chemo- and radiotherapy followed by surgery only marginally affect outcome at the cost of significant morbidity. Because of the long time period between exposure to asbestos and disease onset, the incidence of DMM is still rising and predicted to peak around 2020. Novel markers for the reliable diagnosis of DMM in body cavity effusion specimens as well as more effective, targeted therapies are urgently needed. Here, we show that the "don't eat me" signalling molecule CD47, which inhibits phagocytosis by binding to signal regulatory protein α on macrophages, is overexpressed in DMM cells. A two-marker panel of high CD47 expression and BRCA1-associated protein 1 (BAP-1) deficiency had a sensitivity of 78% and specificity of 100% in discriminating DMM tumour cells from reactive mesothelial cells in effusions, which is superior to the currently used four-marker combination of BAP-1, glucose transporter type 1, epithelial membrane antigen and desmin. In addition, blocking CD47 inhibited growth and promoted phagocytosis of DMM cell lines by macrophages in vitro. Furthermore, DMM tumours in surgical specimens from patients as well as in a mouse DMM model expressed high levels of CD47 and were heavily infiltrated by macrophages. Our study demonstrates that CD47 is an accurate novel diagnostic DMM biomarker and that blocking CD47 may represent a promising therapeutic strategy for DMM.