Hypopigmented Areas Research Articles

Unusual Association: Dermatomyositis Diagnosis Tied to Rare Presence of TPO Autoantibodies

The co-occurrence of autoimmune diseases is prevalent and largely documented. However, the simultaneous presence of dermatomyositis and autoimmune thyroid disorders remains comparably uncommon, despite both being autoimmune in nature. In this report, we present a case of a 60-year-old Bangladeshi American individual delineating clinical manifestations consistent with dermatomyositis, including Gottron's papules, the V-sign, Shawl sign, and skin abnormalities, noticeably hypopigmented areas on the scalp and face. Although muscle biopsy results in this patient did not align strictly with classical dermatomyositis, they illustrated a combination of necrotizing myopathy and dermatomyositis. Notably, laboratory findings conceded the presence of TPO autoantibodies, despite the absence of clinical signs or symptoms of hypothyroidism. This discovery recommends the possibility of an underlying autoimmune thyroid condition. Our case prompts consideration of whether a distinct subtype of dermatomyositis may be associated with autoimmune thyroid conditions, even in the absence of overt thyroid manifestations.

The model of hyper- and hypopigmented structureless areas recognition in the pigmented skin neoplasms

Skin melanoma – dangerous oncological disease which demand a differential diagnostics by clinical algorithms. In order to decrease a subjectivity and increase an accuracy of the medical diagnostics the methods of automation and artificial intelligence are used. There are no common approach to clinical algorithms automation and the topic of a common model of recognition of two variations of the algorithm “modified pattern analysis” important element “structureless areas” is not enough studied. This work is dedicated to development of the model of recognition of hyperpigmented and hypopigmented structureless areas of pigmented skin neoplasms. In the result of the study the developed model provide the possibility to recognize both variations of structureless areas and it’s adequateness if verified in the experiment that includes the processing of 400 images that contain structureless areas. The model accuracy was 83%. The model could be adjusted in future by the increase of the number of image characteristics taken into study and by the increase of the experimental set of images.

Dermoscopic Features of Pigmented Bowen Disease: A Multicenter Study on Behalf of the Ibero-Latin American College of Dermatology (CILAD).

Studies focused on dermoscopic aspects of pigmented Bowen disease (pBD) in Latin American population are scarce and limited to only case reports or small series. To report dermoscopic findings in a large series of 147 pBD diagnosed in Ibero-Latin American population. We conducted a multicentric, retrospective study on 147 histologically proven pBD under the auspices of the Dermoscopy Chapter of the Ibero-Latin American College of Dermatology. The study population consisted of 77 females (52%) and 70 males (48%) with a mean age of 68.6 years. 70.1% of patients had skin phototype 3, 15.6% to skin phototype 2, and 14.3% to skin phototype 4. On clinical examination, near 60% of pBD were flat, 70% presented with scales, and 90% were asymmetric. Under dermoscopy, structureless hypopigmented areas, dots brown and pink color were the most frequently observed. Regarding specific dermoscopic clues to pBD, the most prevalent were structureless hypopigmented areas, vessels arranged in linear fashion at the periphery, and pigmented lines or pigmented dots distributed in a linear fashion. Clustered, coiled, and dotted vessels were observed in 55.8%, 45.6%, and 45.6% of the cases, respectively. We report a large series of cases of pBD in Latin American patients, with most patients being skin phototype 3 and 4. Distinctively in our study, the pigmented structures and the clues derived from the presence of melanin were much more frequent than in previous reports in fair skin.

Investigation of the pathogenesis of ADAR1 gene in dyschromatosis symmetrica hereditaria.

The pathogenesis of dyschromatosis symmetrica hereditaria (DSH) has not been well defined. In this study, we sought to investigate the influence of the ADAR1 gene on DSH both invitro and invivo. Morpholino knockdown of adar1 in zebrafish produced phenotypes characterized by polarity changes, and abnormal migration and distribution of melanocytes. Differential expression of C-KIT and distinct patterns of apoptosis between hyperpigmented and hypopigmented areas in DSH patient were detected by means of immunohistochemical methods and TUNEL assays, respectively. This study revealed that adar1 knockdown in a zebrafish model resulted in abnormal migration and changes in the cell polarity of melanocytes, and provided novel insight into the mechanism of DSH pathogenesis.

Rete ridges are decreased in dyschromic burn hypertrophic scar: A histological study

Dyschromic hypertrophic scar (HTS) is a common sequelae of burn injury, however, its mechanism has not been elucidated. This work is a histological study of these scars with a focus on rete ridges. Rete ridges are important for normal skin physiology, and their absence or presence may hold mechanistic significance in post-burn HTS dyschromia. It was posited that hyper-, and hypo-pigmented areas of scars have different numbers of rete ridges. Subjects with dyschromic burn hypertrophic scar were prospectively enrolled (n = 44). Punch biopsies of hyper-, hypo-, and normally pigmented scar and skin were collected. Biopsies were paraffin embedded, sectioned, stained with H&E, and imaged. The number of rete ridges were investigated. Burn hypertrophic scars that healed without autografts were first investigated. The number of rete ridges was higher in normal skin compared to HTS that was either hypo- (p < 0.01) or hyper-pigmented (p < 0.001). This difference was similar despite scar pigmentation phenotype (p = 0.8687). Autografted hyper-pigmented scars had higher rete ridge ratio compared to non-autografted hyper-pigmented HTS (p < 0.0001). Burn hypertrophihc scars have fewer rete ridges than normal skin. This finding may explain the decreased epidermal adherence to underlying dermis associated with hypertrophic scars. Though, contrary to our hypothesis, no direct link between the extent of dyschromia and rete ridge quantity was observed, the differences in normal skin and hypertrophic scar may lead to further understanding of dyschromic scars.

Waardenburg syndrome - Report of two cases

Waardenburg syndrome (WS) is a group of genetically heterogeneous disorders characterised by white forelock of hair, heterochromia irides, blue eyes, and sensorineural hearing loss as main characteristics. A 3-year-old girl presented with pre-lingual deafness and mild delay in developmental milestones. Both parents were deaf since childhood. On examination, she had a white forelock, heterochromia iridium, dystopia canthorum and hypopigmented areas noted in the distal end of all four limbs. A 1-year-old girl presented with pre-lingual deafness. Other milestones are normal for age. On examination, the baby was not responding to sound, and white forelock, heterochromia iridium, dystopia canthorum and hypopigmented skin over the dorsum of hands and legs were present. Mother also has a white forelock and dystopia canthorum. Brain stem auditory-evoked potentials in both cases showed bilateral auditory pathway dysfunction. Based on the above findings, a diagnosis of WS type-1 (WS-1) was made in both and confirmed by genetic testing. Clinical features of the skin, hair changes, and hearing impairment with language delay with a family history that we should consider WS-1.

CPC09 New-onset agminated Spitz naevi following hypopigmented pityriasis lichenoides chronica

Abstract A 9-year-old girl presented to dermatology with erythematous scaly patches affecting her legs and arms, and hypo­pigmented patches affecting the trunk. She was otherwise fit and well, with no preceding illness or new medications. Treatment with mometasone 0.1% and an emollient was unsuccessful. Two years later, she had continued to develop new hypopigmented patches, as well as dark clustered naevi on the trunk. An incisional biopsy was taken from a hypopigmented patch of the right abdomen and one of the new naevi from the right hip. Incisional biopsy of the hypo­pigmented patch showed scattered necrotic keratinocytes in the epidermis with mild hydropic degeneration of basal cells and a mild superficial and perivascular lymphohistiocytic infiltrate in the dermis, consistent with pityriasis lichenoides chronica (PLC). Incisional biopsy of an eruptive naevus showed a junctional proliferation of melanocytes with overlying epidermal hyperplasia and hyperkeratosis and transepidermal elimination of melanin. Nests of epithelioid melanocytes were present at the rete tips, with no pagetoid spread and no atypia, consistent with an eruptive Spitz naevus. PLC is a benign lymphoproliferative disorder, typically presenting with erythematous scaly papules that relapse and remit. However, cases of PLC presenting with hypopigmentation alone have also been reported, as in this case, which can be part of a postinflammatory dyspigmentation or active disease (Elbendary A, Abdel-Halim MR, Youssef R et al. Hypopigmented lesions in pityriasis lichenoides chronica patients: are they only post-inflammatory hypopigmentation? Aust J Dermatol 2021; 63:68–73). The clustered pattern of Spitz naevi in this patient is termed agminated Spitz naevus. Eruptive disseminated and agminated Spitz naevi are much rarer than the solitary presentation. Triggers of eruptive Spitz naevi include pregnancy, blistering disorders and topical tacrolimus, and in one case following pityriasis lichenoides et varioliformis acuta (Mazzurco J, Menssen K, Schapiro B et al. Eruptive disseminated Spitz nevi in a 26-year-old African-American woman. Int J Dermatol 2012; 51:1270–1), while agminated Spitz naevi are reported to occur after radiotherapy and sunburn, and to arise in naevus spilus or congenitally hypo- or hyperpigmented patches. No cases of malignancy in agminated or eruptive disseminated Spitz naevi have been reported. In this case, the new onset of agminated Spitz naevi may have been triggered by the inflammatory process of PLC. As far as we can ascertain, there have not been previous cases of this published in the literature. Our patient’s hypopigmented areas have now started to self-resolve and we have planned for ongoing monitoring of the agminated Spitz naevi.

The story of melanocyte: a long way from bench to bedside.

Skin is composed of major layers, namely a superficial epidermis and a deeper dermis. The color of skin is influenced by a number of pigments, including melanin, which is produced by cells called melanocytes. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal. A number of more noticeable disorders, namely albinism and vitiligo, affect the appearance of the skin and its accessory organs. Vitiligo is associated with significant psycho-social morbidity and a major effect on quality of life. Topical steroids, calcineurin inhibitors, phototherapy and surgery are the most common treatments for melanoma. However, there are many patients who do not respond to any of these modalities. The transplantation of cultured or non-cultured melanocyte is the most important treatment for hypopigmentory disorders. This study aims at reviewing the history of melanocyte cultivation, and evaluating the effectiveness of transplantation of cultured cells. For this purpose, the authors examined the initial process of isolation, characterization, and transplantation of epidermal cells. This review, thus, summarizes the current understanding of the cutaneous pigmentary system from the start of synthesis in the pigment cells, along with the response of repigmentation. During the production of melanin, melanosomes are transferred to neighboring keratinocyte in order to form perinuclear melanin caps. The objective of this review is to analyze the melanocytes transplantation in the last century to date, and explore the methods epidermal cells can increase pigmentation in hypo-pigmented areas in skin disorders. Moreover, the focus is on the story of the melanocyte back to 1950s. In addition, prior systemic therapy was associated with a significant increase, based on combined additional therapy, achieving desired results and improved outcomes. Despite the short study of a long way of melanocyte assessment and following up patient treatment, results of the all reports confirmed the efficacy of the method used in the treatment of stable vitiligo patients, who did not respond to the common algorithms of non-invasive treatments.

Retro-mode imaging of gravitational subretinal fluid associated with optic disc pit maculopathy with extensive retinal schisis in a young myopic patient

A 32-year-old female with high myopia and optic disc pit maculopathy associated with schisis was imaged on the Mirante confocal scanning laser ophthalmoscope (Nidek Co, Ltd, Gamagori, Japan). Scanning laser ophthalmoscope colour fundus photography (A) shows a hypopigmented area corresponding with the schisis (green arrows), whereas the blue-light fundus autofluorescence (B) highlights an oval hyperautofluorescent area consistent with the subretinal fluid (SRF; white arrow), which is a useful landmark to monitor the extension and localization of the fluid during the course of follow-up. Retro-mode illumination (C) demonstrates enhanced visualization of the margin of the SRF (white arrow). The myopic schisis is highlighted on retro-mode illumination (green arrows) as fine radiating lines. Optical coherence tomography demonstrates the schisis associated with subretinal fluid (D). Panel E illustrates more subtle, smaller areas of schisis adjacent to the SRF.

Dermoscopic Features of Lichenoid Pseudovesicular Papular Eruption of the Nose (LiPEN): A Rare Entity.

Dermoscopic Features of Lichenoid Pseudovesicular Papular Eruption of the Nose (LiPEN): A Rare Entity.

Vitiligo Development after COVID-19 Vaccination

In this study, we present a 64-year-old African American woman with hypopigmented macular areas on her face, hands, and trunk. The lesions first appeared on her hands in early summer of 2021, three months after receiving the first dose of the Moderna COVID-19 vaccine, eventually spreading to her face, abdomen, and back. The patient has a history of Systemic Erythematous Lupus (SLE), currently on Plaquenil, with autoimmune testing positive for ANA and anti-SSB. She reported no personal or family history of vitiligo. She was first examined by Rheumatology and was prescribed a trial of CellCept but discontinued using it due to blistering on her face. She was then referred to a Dermatology clinic. On examination, there were depigmented white macules and patches consistent with vitiligo. The diagnosis was confirmed upon dermatological and woods lamp examination. She was prescribed a topical calcineurin inhibitor and was instructed to return to the clinic for follow-up.

Case Report of Dermoscopic Aspects and Reflectance Confocal Microscopy Description of Segmental Leiomyoma and Relative Management

Cutaneous leiomyoma is a benign tumor, mainly composed of smooth muscle cells and arising from the arrector pili muscle of hair follicles. The diagnosis of leiomyomas is of paramount importance, as they can often be associated with underlying malignancies (e.g., renal cell carcinoma, leiomyosarcoma) and specific genetic mutations. We report the case of a 27-year-old Caucasian male patient that presented to our attention with a rare segmental and Zoosteriform type II leiomyoma. We performed an analysis of the cutaneous lesions using dermoscopy, reflectance confocal microscopy (RCM) and histology. We found that, using dermoscopy, the leiomyomas showed a dermatofibroma-like appearance with a central hypopigmented area, peripheral delicate hyperpigmentation and also erythematous areas and ectatic vessels. RCM, although not specific, showed groups of hypo-reflective areas distributed in the most superficial papillary dermis, which in histology and immunohistochemistry corresponded to the most superficial protrusions in the papillary dermis of the tumoral bundles. Finally, we discuss the management of patients with multiple leiomyomas and stress the fact that, in the cases of multiple leiomyomas, an annual sonography of the kidneys associated with dermatological and (in women) gynecological consultations are needed to ensure the early identification of an underlying tumor. A genetic consultation to detect an eventual FH mutation is recommended, but since in some cases the FH result may be negative, the above recommended controls remain always of paramount importance.

The "hypopigmented" bitemark: a clinical and histologic appraisal.

So-called "hypopigmented" bitemark patterns, commonly seen but not limited to dark skinned individuals, can be of value in forensic investigations. The process of aging bitemarks observed on skin is controversial and without guidelines. This report analyzes tissue obtained from the site of a hypopigmented bitemark using special histochemical stains for the identification of melanin pigment, and a panel of immunohistochemical markers to aid in the aging process. Histologic evaluation clearly showed that cellular changes in the hypopigmented area were indicative of wound healing that had taken place over a period of time. This validates the hypothesis that a hypopigmented bitemark is an indication of a wound inflicted some days previously. These findings have value in forensic investigations, particularly in cases of suspected long-term physical abuse.

Pigmented squamous cell carcinoma in situ with amyloid deposition mimicking melanoma

Pigmented squamous cell carcinoma in situ with amyloid deposition mimicking melanoma

Transient cutaneous hypomelanosis after cryoanesthesia.

A superficial skin abscess in a young black female patient was incised after cryoanesthesia with tetrafluoroethane spray. A hypopigmented area was found at the first follow-up visit in the treated skin area; complete repigmentation occurred during the next 4 months. There are no other similar reported cases in the literature. Since long duration and possibly permanent hypopigmentation can occur after cryoanesthesia with tetrafluoroethane, especially in black people, this technique should be used with extreme caution.

Iris Heterochromia and Choroidal Hypopigmentation in Waardenburg Syndrome

A 10-year-old Black boy was referred for possible retinal hemorrhages. His visual acuity was 20/20 in both eyes. Examination revealed complete iris heterochromia, with one blue iris and one brown iris (Fig A). Fundus examination demonstrated diffuse areas of choroidal hypopigmentation (Fig B-C), notably also in the eye with normal iris pigment. OCT showed a loss of choroidal reflectivity in areas of hypopigmentation (Fig D). The patient did not have a white forelock or hearing loss, but had facial features of telecanthus and a wide nasal root, consistent with a diagnosis of Waardenburg syndrome (Magnified version of Fig A-D is available online at www.aaojournal.org).

Review. The story of melanocyte: long way from bench to bedside

Skin is composed of major layers, a superficial epidermis and a deeper dermis. The color of skin is influenced by a number of pigments, including melanin. Melanin is produced by cells called melanocytes. Most skin disorders are relatively benign, but a few, including melanomas, can be fatal. A couple of the more noticeable disorders, namely albinism and vitiligo, affect the appearance of the skin and its accessory organs. Vitiligo is associated with significant psychosocial morbidity and profound effect on quality of life. Topical steroids, calcineurin inhibitors, phototherapy and surgery are most common treatments. However, there are many patients who do not respond to any of these modalities. The transplantation of cultured or non-cultured melanocyte is the most important treatment for hypopigmentory disorders. In this study, we are going to assess the history of melanocyte cultivation and evaluate the effectiveness of transplantation cultured cells. We examined the beginning process of isolation, characterization, and transplantation of epidermal cells. This review, summarize our current understanding of the cutaneous pigmentary system from the start of synthesis in the pigment cells, along with the response of repigmentation. During the production of melanin, melanosomes are transferred to neighboring keratinocyte in order to form perinuclear melanin caps. The objective of this review is to analyze the melanocytes transplantation in the last century up to now, and how epidermal cells can increase pigmentation in hypo-pigmented areas in skin disorders. Also, we focus on the story of the melanocyte back to 1950. In addition, prior systemic therapy was associated with a significant increase significant increase based on combined additional therapy, achieving desired results and improved outcomes. Despite the short study of a long way of melanocyte assessment and follow up patient's treatment, results of the all reports were confirmed the efficacy of the used method in the treatment of stable vitiligo who did not respond to the common algorithms of non-invasive treatments.

Наследственные дисхромии кожи, протекающие с поражением нервной системы: два случая из практики и обзор литературы

В работе представлено описание 2 пациентов с синдромом Блоха — Сульцбергера и гипомеланоза Ито, пролеченных на базе АО «Республиканский детский реабилитационный центр» в 2015 г. Оба заболевания в дерматологии относятся к группе генодерматозов с дисхромиями кожи, а в неврологии — к группе факоматозов. Генетическая природа заболевания однозначно расшифрована при синдроме Блоха — Сульцбергера: заболевание развивается вследствие мутации NEMO/IKK-γ-гена, расположенного на хромосоме Xq28; гипомеланоз Ито считается проявлением хромосомного мозаицизма, хромосомная патология обнаруживается не во всех случаях заболевания. Оба заболевания проявляются типичными кожными изменениями, которые при синдроме Блоха — Сульцбергера дебютируют в период новорожденности и претерпевают 4 стадии изменений; при гипомеланозе Ито участки гипопигментации появляются в возрасте до 2 лет. Представленные нами пациенты помимо характерных кожных проявлений заболеваний имели симптомы поражения нервной системы.

Congenital Epidermodysplasia Verruciformis in Skin of Color: New Dermoscopic Features.

Sir, Epidermodysplasia verruciformis (EDV) is a rare inherited disorder associated with infection of human papillomavirus (HPV). Only a few authors have described the dermoscopic features in EDV.[123] We hereby describe newer dermoscopic features in a rare case of congenital EDV in an Indian family. A 24-year-old female presented to us with multiple white to reddish-brown coloured flat lesions on the trunk, and upper and lower limbs since birth. Her two children, that is, a six year old girl and four year old boy also had similar lesions. However, there was no similar history among the parents or siblings of the patient. Cutaneous examination revealed multiple well-defined erythematous to hypopigmented macules resembling pityriasis versicolor (PV) along with multiple well-defined, verrucous dark-brown coloured plaques of size approximately 1 × 1 cm2 on chest, abdomen, back, and all extremities [Figure 1a and b]. Other dermatological and systemic examination were normal. Complete blood count, serum biochemistry, and urine analysis were normal. Human immunodeficiency virus (HIV), Hepatitis B antigen (HbsAg), and anti-Hepatitis C antibodies (anti-HCV) serology were non-reactive.Figure 1: (a and b) Multiple well-defined hypopigmented (pityriasis versicolor-like) and dark brown keratotic lesionsDermoscopy was done using Dermlite DL-4 under 10× polarized mode. It revealed hypopigmented to erythematous background with red dots, white scaling, and slight crusting in hypopigmented/PV-like macules [Figure 2a]. Margins of most of the lesions had a characteristic continuous scaling [Figure 2a and b]. Verrucous plaques showed brownish-black areas admixed with hypopigmented areas [Figure 2c]. Histopathological examination of skin biopsy showed basket-weave hyperkeratosis, parakeratosis, and mild acanthosis of epidermis. Keratinocytes in the superficial layers were enlarged and swollen with abundant basophilic cytoplasm containing numerous round keratohyaline granules did not mention about vacuolation? Upper dermis showed mild perivascular lymphoplasmacytic infiltrate [Figure 2d]. A final diagnosis of EDV was made. The patient was started on oral isotretinoin.Figure 2: (a) Hypopigmented (pityriasis versicolor-like) lesions: Showing hypopigmented to erythematous background with red dots (orange arrow) and lesional white scales (green arrow) and continuous marginal scaling (black arrows). (b) Continuous marginal scaling (black arrows), brownish-black areas admixed with hypopigmented areas (pink arrows).(c) Admixture of hypopigmented areas with brownish-black areas (red circle). (Dermlite DL-4;10× polarised mode) (d) Basket weave hyperkeratosis and parakeratosis and enlarged keratinocytes with swollen abundant basophilic cytoplasm containing keratohyaline granules (H&E 40x)EDV is characterised by an impairment of cell-mediated immunity which results in disseminated skin eruptions by HPV clinically presenting with lesions resembling PV, verruca plana, and seborrheic keratosis (SK). There are very few reports of EDV, wherein dermoscopic features have been described.[123] Dermoscopy of lesions in EDV has shown demarcated hypopigmented to erythematous background with scaling, unfocused dotted vessels, and diluted hair pigment. SK-like lesions have demonstrated comedo-like openings with abrupt border.[12] Similar findings were seen in our patient except in any lesion, we did not observe dilution of hair pigment, comedo-like opening, or milia-like cysts. Additionally, we observed an admixture of brownish and hypopigmented background with brown globules and a characteristic marginal continuous scaling. These newer features observed in our patient might be due to different skin type and stages of the lesions than the previous reports. A similarity in dermoscopy of different lesions of EDV has been attributed to common etiology.[1] On dermoscopy, the admixture of different areas might also be due to the common etiology and it could be showing different stages of the EDV, which are not yet seen clinically. More such case reports and long-term follow-ups are needed to understand definitive dermoscopic features which would assist in the early diagnosis of malignant transformation. We hereby report this case due to its rarity and paucity of literature regarding its dermoscopic features. Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest. Acknowledgements Renuka Verma, M.D. Pathology, Assistant Professor, Department of Pathology, Pt. BD Sharma Postgraduate Institute of Medical Sciences, Rohtak, Haryana, India (For histopathology pictures).

Intracavitary Electron FLASH Radiotherapy in a Canine Cancer Patient With Oral Malignant Melanoma

Studies of electron FLASH radiotherapy (FLASH-RT) in companion animals are being conducted at several institutions. High energy electron beams are generally suitable for treatment of superficial cancers, but of limited use for deep-seated tumors. In this case report, the feasibility of intracavitary electron FLASH-RT is demonstrated.A canine cancer patient with a large oral malignant melanoma in the caudal part of the hard palate was palliatively treated with FLASH-RT at a modified clinical linear accelerator, using a cylindrical PMMA applicator (length 200 mm, inside diameter 50 mm). The patient had a poor prognosis, with an estimated survival of two weeks and no other available treatment options. A dose of 35 Gy was delivered to the depth of dose maximum in 26 pulses with a pulse dose rate of 4.5•105 Gy/s. The average dose rate was 280 Gy/s, corresponding to a total beam-on time of 125 months. One month after the treatment, the tumor was re-irradiated, using the same treatment parameters. The treatment head of the LINAC was fitted with a short electron applicator holder with a Cerrobend collimator at 65 cm from the source. The cylindrical PMMA applicator was aligned perpendicularly to the Cerrobend collimator using soft docking with a 1 cm gap. Prior to the treatments, the 2D dose distribution of the FLASH beam exiting the PMMA applicator was measured with radiographic film. In addition, the dosimetric effect of misalignment between the collimator and the electron applicator was studied based on intentional misalignments of 2.5°, 5°, 2.5 mm, and 5 mm.A partial response of the tumor and clinical improvement of the patient was observed two weeks after the first treatment. A hypopigmented area in the hard palate was observed, consistent with a grade 1 adverse event, but there were no signs of mucositis or reports of patient discomfort. However, due to the thickness of the tumor (> 3 cm), the posterior part only received a limited dose, and the tumor was still obstructing the airflow at one month post treatment. At this time, a second treatment was administered with limited normal tissue receiving full dose from both treatments. At one month post the second treatment, a partial response was achieved, and no evidence of side effects other than hypopigmentation was observed. The patient was euthanized 2.5 months after the initial therapy due to progressive disease involving the oropharynx. The dosimetric evaluation showed that a conformal dose distribution could be obtained by delivering the electron beam using a cylindrical PMMA applicator. Misalignments between the applicator and the collimator were shown to result in reduced dose homogeneity.This case report of a canine cancer patient, with a large oral malignant melanoma in the caudal part of the hard palate, has demonstrated the feasibility of intracavitary electron FLASH-RT. Two treatments of 35 Gy each, resulted in prolonged survival and increased quality-of-life.