Orofacial Cysts: A Single Institution Experience of 85 Cases in Enugu, Nigeria.

BACKGROUND: Orofacial cysts are pathologic cavities that could be symptomatic and may cause facial disfigurement. The only epidemiologic report of such lesions in Southeast Nigeria studied jaw cysts from 1987 to 1996. New studies reflecting recent research findings and classifications on the subject in Southeast Nigeria are lacking. AIM: To determine the prevalence and distribution of orofacial cysts in a tertiary hospital in Enugu, Southeast Nigeria. METHODS: A 10-year retrospective study of patients with orofacial cysts diagnosed by histology was carried out. RESULTS: Orofacial cysts constitute 9.5% (85) of 897 orofacial lesions identified. The male-to-female gender ratio was 1.2:1. The mean age (± standard deviation) at the onset of the cystic lesion was 28.58 (±16.98) years. Developmental odontogenic cysts 52.9% (45) and salivary cysts 18.8% (16) were the most common group of orofacial cysts. The most prevalent orofacial cysts were odontogenic keratocysts at 25.9% (22), mucoceles 16.5% (14), and dentigerous cysts 14.1% (12). Straw-colored aspirates 34.8% (16) and dark brown aspirates 28.3% (13) were the predominant cystic contents. The mandible 45.9% (39) and maxilla 27.1% (23) were the commonest sites for orofacial cysts, while the lip 9.4% (8) was the most frequent soft tissue site. A significant association exists between anatomical site and cyst type at a 95% confidence interval with P = 0.000, X2 = 247.17. Unilocular radiolucency 62.5% (20) and multilocular radiolucency 34.4% (11) were the most common radiographic features. CONCLUSION: Developmental odontogenic cysts particularly odontogenic keratocysts were most prevalent while mucocele was the most common soft tissue cyst.

What factors influence mucocele recurrence?

OBJECTIVE: The purpose of this study was to identify whether age is associated with mucocele recurrence after excision. STUDY DESIGN: This retrospective cohort study consisted of 492 patients who underwent oral mucocele excision at Boston Children's Hospital from 2010 to 2022. Fisher's exact tests were used to assess the association between age and mucocele recurrence. An adjusted logistic regression model was run to evaluate the effect of age on mucocele recurrence while controlling for confounders. A P value < .05 was considered significant. RESULTS: Mucocele recurrence was observed in 24 cases (4.9%). There was a significant association between age and mucocele recurrence (2.2% for <7 years vs. 2.9% for 7 to <13 years vs. 9.2% for 13 to <18 years vs. 8.9% for >18 years; P = .005). Sex; history of behavioral disorders; mucocele size, duration, and location; suture technique; and type of anesthesia were not significantly associated with recurrence (P > .135). An adjusted logistic regression model verified a significant association between age and mucocele recurrence (odds ratio, 1.053; 95% confidence interval, 1.019-1.088; P = .035). CONCLUSIONS: Mucocele recurrence occurs infrequently in patients younger than 7 years and is most prevalent in the teenage to young adult patient population. For every year increase in age, the odds of mucocele recurrence increase by 5.3%.

HPV related p16INK4A and HSV in benign and potentially malignant oral mucosa pathologies.

BACKGROUND: The association of Human Papilloma Virus (HPV) and Human Syncytial Virus (HSV) infection with inflammatory and potentially malignant disorders of the oral cavity (OPMD) is unknown. The aim of this cross-sectional study was to stablish the expression of the p16INK4A and HSV proteins, to test potential correlation between those parameters in biopsies from clinically diagnosed oral lesions. METHODS: Immunochemical analysis of 211 formalin-fixed, paraffin-embedded (FFPE) blocks from 211 individuals was provided. The clinical diagnosis included in the research were Oral lichen planus (N = 30), Oral Leukoplakia (N = 13) Mucocele (N = 25), Erosion/ulceration/ inflammation of mucosa (N = 8), Overgrowth of mucosa (N = 135). RESULTS: Two hundred eleven analyzed FFPE samples resulted with the median age of 58.5 years (the average age 54.0 years and SD ± 17 years). The female/male ratio was 2.3 (69.7% vs 30.3% respectively). All the samples positive for HSV also expressed p16INK4A (p = 0.000), that's showed various levels of association with the diverse clinical diagnosis reaching the higher level in OM 49.1% (29 positive samples) and OLP 30.5% (18). p16INK4A was associated with OLP at 30.5% (18), and fibroma 30.5%. HSV expression was mostly present in fibroma at 47.6% (10 positive samples). CONCLUSION: HSV and p16INK4A positivity in relation to diagnosis of the biopsies showed statistically most often p16INK4A in OLP and fibroma. The results of co-expression of p16INK4A and HSV in mucocele and fibroma in oral mucosa suggest a cooperation between the molecular alterations induced by these two viruses. Squamous papilloma samples positive for p16INK4A were also positive for HSV, suggesting that the putative pro-oncogenic action of HSV could be an early event.

The Cancer Diaspora: A Rare Case of Pseudomyxoma Peritonei of Appendiceal Origin.

Pseudomyxoma peritonei (PMP) is a rare clinical entity characterized by widespread mucinous implants in the peritoneal cavity. Commonly seen in females in their 50s, PMP typically originates from ruptured appendiceal mucoceles that find refuge in the peritoneal space. Rarely, PMP may originate from the ovary, stomach, colon, or pancreas. Pseudomyxoma peritonei of colorectal origin is more malignant and has a lower survival rate. We report a case of a 59-year-old Hispanic woman with PMP who presented to the emergency room with a 3-month history of progressive abdominal distention. Pseudomyxoma peritonei was confirmed by computed tomography (CT) scan of the abdomen and pelvis and histopathology, and the patient underwent partial cytoreductive surgery. Given her Eastern Cooperative Oncology Group (ECOG) performance status of 1 despite extensive carcinomatosis, our patient may benefit from hyperthermic intraperitoneal chemotherapy (HIPEC) in the future.

Tongue Mucoceles: a retrospective clinic-pathological evaluation of 240 cases.

BACKGROUND: Minor salivary glands can be found in the ventral and anterior part of the tongue; these glands can rarely develop mucoceles that, due to their rarity and their unusual clinical appearance, may present an interesting differential diagnosis. Mucoceles appear as an exophytic, sometimes pedunculated, lesion, which is a feature that is due to the absence of a capsule; thus, the glands are right beneath the mucosa and over the muscle tissue. The aim of this article is to retrospectively present and discuss the anatomy, pathology, clinical features and therapy of several cases of Blandin-Nunh mucoceles collected from two different institutions. METHODS: A retrospective case review was carried out in two university institutions, retrieving all cases of tongue mucoceles from 1999 to today. Two oral pathologists reviewed all the slides, confirming the diagnosis. Demographic data of the patient, anatomic location and clinical appearance were retrieved from clinical charts, together with the type of surgical procedure and possible relapses. RESULTS: A total of 240 cases of tongue mucoceles were gathered from the archives: the mean age was 22 years (DS = 14,7; Range 2-83), 126 were females (52,5%, mean age 22,7 years, DS = 16,5; Range 2-83), and 114 were males (47,5%, mean age 20,9 years, DS = 12,4; Range 3-73); in all cases, a history of trauma was reported. The ventral surface was the most frequent location (224 cases - 93,3%), and in the great majority (235 cases - 97,9%), pathology revealed mucous spillage with a wall formed by fibrous connective and granulation tissue with no epithelium lining the cavity. Superficial mucocele and sclerosing sialoadenitis were the more frequent pathological variants (21 cases - 8,8%). All lesions were treated with excision and enucleation of the servicing gland. The healing was uneventful in all cases, but there were four recurrences and two cases of sensory paraesthesia of the border of the tongue, all in males, except one case of paraesthesia in a female. CONCLUSIONS: Tongue mucoceles must be differentiated from many benign and malignant lesions. For this reason, surgical removal of the lesion and of the associated gland with a pathological exam is mandatory. In fact, the anatomical location of the glands and the possible pathological variants must be considered to reach a correct diagnosis and diminish possible relapses. TRIAL REGISTRATION: CE-Muc_Ton_3/2023.

Superficial mucoceles in cancer patients: a retrospective series from a Stomatology unit

Background: The aim of this study is to relate all the superficial mucoceles found in a cancer center, described the association with oncological conditions, and discuss its etiology and pathology that we found in the past few years. Material and Methods: Sixteen cases of superficial mucocele were retrieved from the patients’ records of the Stomatology Department of the A. C. Camargo Cancer Center, São Paulo, Brazil, and demographic and clinical data were collected from electronic medical records. Results: There were 16 patients, 8 patients were men and 8 women, with ages varying from 26 to 70 years old. Superficial mucoceles were observed in patients submitted to head and neck radiotherapy (n=6), graft versus host disease (n=4), one associated with oral mucositis related to allogenic bone marrow stem cells transplantation (n=1), systemic lupus (n=1), Sjögren’s syndrome (n=1), oral lichenoid lesion associated with pembrolizumab (n=1) and no local or systemic inflammatory associated found (n=2).Conclusions: This study reports a series of superficial mucoceles from a single stomatology unit. Most patients had superficial mucoceles secondary to head and neck radiotherapy and graft versus host diseases. However, two patients (12.5%) had mucoceles related to systemic inflammatory conditions (Sjögren’s Syndrome and Systemic Lupus). (AU)

Spectrum of Mucin-containing Lesions of the Breast: Multimodality Imaging Review with Pathologic Correlation.

Mucin-containing lesions of the breast encompass a wide range of benign and malignant processes. The spectrum of histologic findings includes incidental mucus-filled benign cysts or ducts, mucocele-like lesions (MLLs), mucin-producing ductal carcinoma in situ, and invasive mucinous carcinoma. MLL is characterized by the presence of mucin-containing cysts that are typically associated with extravasated stromal mucin. MLL is often benign but can be associated with epithelial atypia or malignancy. Mucinous carcinoma represents the malignant end of the spectrum of mucinous lesions of the breast. Evidence-based literature supports a conservative approach for benign MLLs without associated atypia or malignancy, reserving excision for those lesions exhibiting such pathologic features. The most common imaging finding for MLL is microcalcifications at mammography. No specific imaging feature is predictive of malignant outcome at surgical excision. Invasive mucinous carcinoma is a heterogeneous breast tumor subtype, as defined according to the World Health Organization criteria. Mucinous carcinomas are categorized into pure (>90% mucinous component) or mixed (10%-90% mucinous component) subtypes. Pure mucinous carcinomas are generally associated with excellent prognosis and survival, with a few exceptions. Mixed mucinous carcinomas do not have the same favorable prognosis and instead behave similarly to invasive breast carcinomas of no special type. Characteristic diagnostic imaging features can be identified for mucinous carcinoma based on its mucinous and nonmucinous contents. ©RSNA, 2023 Online supplemental material is available for this article. Quiz questions for this article are available through the Online Learning Center.

Superficial mucoceles in cancer patients: a retrospective series from a Stomatology unit.

BACKGROUND: The aim of this study is to relate all the superficial mucoceles found in a cancer center, described the association with oncological conditions, and discuss its etiology and pathology that we found in the past few years. MATERIAL AND METHODS: Sixteen cases of superficial mucocele were retrieved from the patients' records of the Stomatology Department of the A. C. Camargo Cancer Center, São Paulo, Brazil, and demographic and clinical data were collected from electronic medical records. RESULTS: There were 16 patients, 8 patients were men and 8 women, with ages varying from 26 to 70 years old. Superficial mucoceles were observed in patients submitted to head and neck radiotherapy (n=6), graft versus host disease (n=4), one associated with oral mucositis related to allogenic bone marrow stem cells transplantation (n=1), systemic lupus (n=1), Sjögren's syndrome (n=1), oral lichenoid lesion associated with pembrolizumab (n=1) and no local or systemic inflammatory associated found (n=2). CONCLUSIONS: This study reports a series of superficial mucoceles from a single stomatology unit. Most patients had superficial mucoceles secondary to head and neck radiotherapy and graft versus host diseases. However, two patients (12.5%) had mucoceles related to systemic inflammatory conditions (Sjögren's Syndrome and Systemic Lupus).

Sphenoid sinus anatomical variants and pathologies: pictorial essay.

The sphenoid sinus (SS) is one of the four paired paranasal sinuses (PNSs) within the sphenoid bone body. Isolated pathologies of sphenoid sinus are uncommon. The patient may have various presentations like headache, nasal discharge, post nasal drip, or non-specific symptoms. Although rare, potential complications of sphenoidal sinusitis can range from mucocele to skull base or cavernous sinus involvement, or cranial neuropathy. Primary tumors are rare and adjoining tumors secondarily invading the sphenoid sinus is seen. Multidetector computed tomography (CT) scan and magnetic resonance imaging (MRI) are the primary imaging modalities used to diagnose various forms of sphenoid sinus lesions and complications. We have compiled anatomic variants and various pathologies affecting sphenoid sinus lesions in this article.

Clinico-radiologic characteristics of lacrimal sac area swellings misdiagnosed as dacryocystocele or mucocele.

PURPOSE: Several non-lacrimal lesions can present with lacrimal sac area swelling mimicking a dacryocystocele or mucocele with a possibility of misdiagnosis. This study investigates the clinic-radiologic characteristics of the mimicking conditions compared to true lacrimal sac distension. DESIGN: Retrospective, comparative, interventional case series. PARTICIPANTS: Patients referred by primary care ophthalmologists between January 2015 and October 2021 with a misdiagnosis of dacryocystocele or lacrimal sac mucocele (n = 39) and an age-matched group of proven true lacrimal sac swelling (TLS group, n = 44). METHODS: Data collected included demographics, presenting features, investigations, management, histopathology, and outcomes. Both groups were statistically compared for several clinical and radiological variables. RESULTS: Final diagnoses in the mimicking group were skin/subcutaneous swellings (14/39, 35.9%), vascular malformations (10/39, 25.6%), inferomedial anterior orbital cysts (7/39, 17.9%), sino-orbital masses (5/39, 12.8%). Female gender (<0.001), epiphora (p = 0.001), and discharge (p < 0.001) were significantly more frequent in the TLS group. The mimicking group was more likely to be associated with a longer swelling duration (p < 0.001), a swelling extending beyond the lacrimal sac area (p <0.001), orbital signs (p <0.001), and periorbital abnormality. Non-patent lacrimal irrigation (p < 0.001) was significantly more frequent in the TLS group. On imaging, all swellings in the mimicking group were separate from the lacrimal pathway and 94.9% (37/39) extended beyond the lacrimal sac fossa. CONCLUSION: Various cutaneous, subcutaneous, vascular, inferomedial orbital cystic, and sinonasal pathologies can present with lacrimal sac area swelling and mimic a TLS. A high index of suspicion, a thorough clinical evaluation and proper imaging are essential to avoid a misdiagnosis.

Utility of flexible interventional endoscopy in endoscopic sinus surgery: a case series.

PURPOSE: During endoscopic sinus surgery (ESS), difficult-to-reach pathologies need an extended endoscopic approach or an external approach. We started to use a flexible interventional endoscope (FIE) to evaluate the necessity of those approaches. The study's objective is to describe our experience and define patients who could benefit from this technique. METHODS: We reviewed every patient who benefited from FIE associated with ESS at our tertiary University Hospital between January 2021 and February 2022. RESULTS: During this period, we did 107 ESS, and 14 patients benefited from the FIE, representing 13% of our ESS. The median duration of the flexible endoscopy time was 14 min (4-38 min). We identified three groups of patients who can benefit from the FIE. The first one is for patients with a fungal infection, to control and to clean lateral recesses in a noninvasive manner. The second one is for patients with a pathology of the lateral frontal sinus, to remove the frontoethmoidal cells or mucocele with the biopsy forceps through the working channel. The third group is for patients with inverted papillomas, to precisely identify the insertion and to decide on the most appropriate surgical approach. CONCLUSIONS: In selected cases, using flexible endoscopy during ESS helps decide the optimal surgical approach and sometimes treat the pathology through a limited approach. Prospective studies for each group of patients are needed to confirm the benefit of this new combined procedure.

Intravascular Papillary Endothelial Hyperplasia of Buccal Mucosa Masquerading as Mucocele - A Case Report.

INTRODUCTION: Oral intravascular papillary endothelial hyperplasia (IPEH) is a rare entity with only 105 cases reported so far. Labial and buccal mucosa are the commonly affected sites. These sites are coincidently subjected to continuous minor trauma, which led the researchers to opine that IPEH could have a traumatic etiology with a further role of fibroblast growth factors. CLINICAL PRESENTATION: We report a case of IPEH of right buccal mucosa in a 35 years old South Indian male who clinically presented as mucocele. Histopathologically, multiple lesions were found. Immunohistochemical and histochemical findings have also been presented. DISCUSSION: The case is supported by a plausible mechanism involved in the pathogenesis. Thus, IPEH must be included in the clinical differential diagnosis of oral mucoceles and hemangioma. TAKEAWAY LESSONS: Being a reactive lesion, it does not require extensive treatment. Clinicians and histopathologists must be aware of this uncommon yet benign condition for appropriate therapy.

Oral mucoceles: A Brazillian Multicenter Study of 1,901 Cases.

Oral mucocele (OM) is the most common lesion of minor salivary glands. The present study aimed to report the clinical and demographic features of a large series of OMs and identify possible predictive variables associated with the recurrence rate of these lesions. A retrospective descriptive cross-sectional study was performed. A total of 43,754 biopsy records from four pathology services in Brazil were analyzed. All cases of OMs were reviewed, and clinical and demographic data were collected. The study comprised 1,002 females (56.2%) and 782 males (43.8%), with a mean age of 19.8±16.4 years (range: 01-87 years) and a 1.3:1 female-to-male ratio. The lower lip (n=1,160; 67.4%), and floor of the mouth (n=172; 10.0%), were the most common affected sites, presenting clinically as nodules (n=978; 79.4%) of smooth surface (n=428; 77.5%) and normal color (n=768, 46.7%). Excisional biopsy was the treatment in most cases (n=1,392; 78.0%). Recurrent OMs represented 6.2% of all diagnosed cases (n=117). OMs recurred more commonly in younger patients (aged<20 years) (p<0.0001), in lesions larger than 2 cm in diameter (p<0.0001), and in those located in the ventral tongue (p=0.0351). Also, recurrence rates were higher significantly in cases treated with laser surgery than in those with conventional surgery (p=0.0005). Patients with OMs should be carefully informed of its possible recurrence, especially when found on the ventral tongue of young patients.

Clinical relationship between histopathological necrotic/partial necrotic findings and disease condition of gallbladder mucoceles in dogs.

Gallbladder mucocele (GM) is a common extrahepatic biliary disease recognized in dogs and is defined as the expansion and extension of the gallbladder by an accumulation of semi-solid bile or bile acid. Histopathological diagnosis of necrotizing cholecystitis and transmural coagulative necrosis of the gallbladder wall shows poor prognosis. Conversely, histopathological diagnosis with partial necrotic findings is often achieved. We hypothesized that histopathological partial necrosis of the gallbladder wall is the primary lesion of necrotic cholecystitis or transmural ischemic necrosis. Therefore, we investigated the relationship between histopathological necrosis/ partial necrosis findings and their clinical conditions. We retrospectively analyzed 55 dogs diagnosed with GM that had undergone cholecystectomy at the Yamaguchi University Animal Medical Center. The group with histopathological necrosis/partial necrosis of the gallbladder wall showed elevated levels of preoperative white blood cells, alanine transaminase, alkaline phosphatase, γ-glutamyltransferase, total bilirubin, and C-reactive protein compared to the non-necrotic group. Partial necrosis of the gallbladder wall may affect the progression of the disease and hematological abnormalities. Additionally, all death cases until 2 weeks were included in the histopathological necrosis/partial necrosis group. In this study, we found that poor prognosis factors were associated with partial necrosis of the gallbladder wall. Furthermore, these cases of partial necrosis showed elevated levels of blood test parameters. These results suggest that necrosis of the gallbladder wall is associated with poor prognosis and poor pathophysiological conditions.

Selection of mucocele management technique: considerations in pediatric patients.

The objectives of this article are to describe the surgical excision of an oral mucocele in a 9-year-old boy and to examine the literature on mucocele management approaches, highlighting their advantages and disadvantages in terms of a patient's ability to cooperate in the dental chair. In the present case, a 9-year-old boy who was known to be a cooperative patient underwent conventional surgical excision and tolerated the procedure well. A review of the literature from 2010 to 2018 revealed 20 relevant studies outlining a variety of approaches to mucocele management, including surgical excision, intralesional corticosteroid injection, laser removal, micromarsupialization, cryosurgery, and withholding treatment for cases in which a lesion is small and allowed to spontaneously regress. While conventional surgical excision of mucoceles is suitable for cooperative patients, alternative approaches may offer reduced chair time, minimal intraoperative bleeding, and enhanced postoperative recovery. For pediatric patients who demonstrate maladaptive behavior, certain treatment modalities may prove superior to surgical excision for the management of mucoceles.

Multidrug resistant Enterococcus faecium isolate from cholangitis/cholecystitis in a dog.

Mucocele and cholecystitis were diagnosed in a 10 year-old Shetland-sheepdog presenting aspecific clinical signs. Blood examinations and ultrasonography investigation were performed before to surgical approach, which allowed to collect biopsies and samples for bacteriological analyses. In addition, the patient was subjected to cholecystectomy. A multidrug resistant Enterococcus faecium was isolated from the gallbladder specimens. On the basis of antimicrobial susceptibility test, nitrofurantoin was used. The correct bacteriological diagnosis is necessary to set up effective therapy, influencing the patient's prognosis and improving the recovery time.

Clinical outcome and quality of life of lacrimal sac mucocele treated via endoscopic posterior approach.

OBJECTIVE: Dacryocystorhinostomy (DCR) is the surgical treatment for lacrimal sac mucoceles (LSM), yet variants of the procedure are several. Since LSM causes bone remodeling and thinning, especially of the lacrimal bone, osteotomy at that site is reasonably the easiest. The aim of the study is to support treatment of LSM via a posterior DCR approach, in a large cohort of cases, and report patients' quality of life after the procedure with validated questionnaires. METHODS: Single-center observational retrospective study on a specific methodology (endoscopic-DCR via posterior approach). Consecutive patients with LSM were enrolled in 2008-2020; CT scans were reviewed, bone thickness was measured bilaterally and compared. Resolution of mucocele, epiphora and infection were analyzed after 6-months. Patients were administered the Munk Score and Lacrimal Symptom Questionnaire (Lac-Q). Statistical analysis was done to compare bone thickness between the two sides; descriptive analysis of the questionnaires results was presented. RESULTS: Forty-four patients with LSM were enrolled. The LSM side showed frontal process thickness of 4.00 ± 1.06 mm (vs 3.90 ± 1.03 on the unaffected side; p = 0.23) and a lacrimal bone of 0.32 ± 0.12 mm (vs 0.41 ± 0.12; p < 0.001). Resolution of infection was achieved in 97.4% cases, anatomical patency in 87.2%. After 5 years, 84.6% of patients reported no relevant epiphora (Munk score 0-1). Social impact (Lac-Q) due to lacrimal malfunctioning was still noted in 30.8% patients. CONCLUSIONS: Adult LSM is a rare condition and DCR remains the mainstay of treatment. LSM physiopathology may support a preferred surgical choice via a posterior approach. Despite objective patency, some lacrimal way malfunctioning may be experienced in a minority of cases.

Mucin Neovascularization as a Diagnostic Aid to Distinguish Mucinous Carcinomas From Mucocele-like Lesions in Breast Core Needle Biopsies.

The distinction between mucinous carcinomas (MCs) and mucocele-like lesions (MLLs), particularly those containing detached epithelial fragments, can be problematic in the limited samples afforded by breast core needle biopsies (CNBs). Neovascularization of mucin has been proposed as a criterion to distinguish MC from MLL, but its value in helping to categorize mucin-producing breast lesions in CNB has not been previously investigated. To address this, we evaluated mucin neovascularization on hematoxylin and eosin (H&E)-stained sections of 140 CNB containing mucin-producing breast lesions including 52 MC, 17 mucin-producing ductal carcinoma in situ (mDCIS), and 71 MLL. In 116 cases with sufficient remaining material (42 MC, 16 mDCIS, and 58 MLL), we also assessed mucin neovascularization on CD31 immunostains. On H&E-stained sections, neovascularization of mucin, defined as delicate, thin-walled microvessels in mucin, and unassociated with fibrous septae, was identified significantly more frequently in MC than in MLL (69.2% vs. 14.1%; P=0.0001). The difference in the frequency of mucin neovascularization between MC and MLL was even greater on CD31 immunostains (97.6% vs. 13.8%, P<0.00001). The sensitivity, specificity, positive predictive value, and negative predictive value of mucin neovascularization for categorizing a lesion as MC were 69.2%, 85.8%, 78.3%, and 79.2%, respectively, for H&E-stained sections and 97.6%, 86.2%, 83.7%, and 98.0%, respectively, for CD31 immunostains. We conclude that mucin neovascularization is significantly more common in MC than in MLL in breast CNB on H&E-stained sections and particularly on CD31 immunostains and may be a valuable adjunct in distinguishing between MC and MLL in problematic cases.