Focal cutaneous telangiectasia in a young dog of probable congenital origin
INTRODUCTION Cutaneous vascular anomalies form a heterogeneous disease group that would be categorised into tumours and malformations in human medicine according to clinical and biological criteria (Calonje et al., ; Dompmartin et al., ; Goldsmith et al., ; ISSVA, ). A new classification (International Society for the Study of Vascular Anomalies [ISSVA], ) for human vascular anomalies has been proposed in 2018 by the ISSVA. The ISSVA ontology has been created to represent a sharable semantic data model of the ISSVA classification. Cutaneous vascular anomalies in dogs include cutaneous haemangiomas, haemangiosarcomas, lymphangiomas, lymphangiomatosis, lymphangiosarcomas, angiomatosis, telangiectasias and vascular naevi or hamartomas (Gross et al., ). Telangiectasia is defined as permanent dilation of pre‐existing blood vessels, creating small focal lesions, usually in the skin or mucous membranes. In the dog, telangiectasia may appear as a cutaneous feature of canine hyperadrenocorticism. Additionally, Demanuelle et al.  described chronic cutaneous telangiectasia in an old dog without an apparent underlying cause. Herein we present the first case of a young dog with idiopathic cutaneous telangiectasia. The nomenclature and classification for cutaneous telangiectasia in dogs were reviewed, and the case was discussed in relation to the classification for human vascular anomalies. 

CASE REPORT 2.1 Case history An 18‐month‐old spayed female Maltese dog presented with demarcated erythema of the skin on the right thorax (Figure ). The lesion was first noticed 2 months prior to presentation and remained stable throughout the follow‐up period. The owner was unsure when the lesion appeared because they had not paid careful attention to see the skin under the hair coat. The lesion consisted of scattered, florid, ramified macules (Figure ), with mild dermatrophia and desquamation. The dog was otherwise healthy and there was no history of using drugs including flea and tick prevention treatments. 2.2 Diagnostic procedure Clinical differential diagnoses included capillary haemangiomas, cutaneous vascular naevi, telangiectasia, cutaneous angiomatosis and secondary phenomena related to circulatory, coagulation, and endocrine disorders. Diascopy revealed a blanchable lesion. Dermoscopy was performed with Derma 9500 (Derma Medical Inc., Yokohama, Japan) combined with a PowerShot A630 camera (Canon Inc., Tokyo, Japan). The capillaries demonstrated a reticular appearance, and those in the superficial dermis showed dilation, different sizes and irregular linear or tortuous patterns in magnified views (Figure ). In contrast, the healthy skin did not show an erythematous colour change, and the capillaries appeared as thin red lines. Skin biopsy was performed with a 6‐mm biopsy punch under local anaesthesia; bleeding and purpura were not observed at either site after biopsy. Histopathological examination of the lesion revealed focal moderate dilation of the congested capillaries at the superficial dermis (Figure ). In addition, some of the vessels in the lower dermis and subcutaneous adipose tissue were mildly dilated. The dilated capillaries were lined by a single layer of uniform endothelial cells (Figure ). There were no obvious morphological abnormalities such as atypia or mitoses. In a biopsy of the healthy skin from over the left shoulder, capillary dilation was not observed. We performed Elastica van Gieson (EVG) staining, which showed as expected that the small, dilated capillaries lacked intimal elastic membrane (Figure ). Immunohistochemical staining using antibodies for alfa‐SMA (Mouse Monoclonal Antibody, Clone 1A4, 1:5000, SIGMA, USA) was also performed. It was shown that the dilated vessels, similar to the normal ones in the not affected skin, were surrounded by few positive cells interpreted as the pericytes (Figure ) (Alarcon‐Martinez et al. ; Nehls V et al, ). Based on the clinical and histopathological findings, an idiopathic cutaneous telangiectasia was diagnosed. 2.3 Treatment and outcome The lesion was followed up over 3 years by regular medical checks without any treatments. The margin of the lesion expanded slightly, and the vasodilation appeared to be mildly accentuated (Figure ). However, the morphological pattern and distribution of lesions remained essentially the same as that of the original presentation, and the general condition was good during the follow‐up period. 

Case history An 18‐month‐old spayed female Maltese dog presented with demarcated erythema of the skin on the right thorax (Figure ). The lesion was first noticed 2 months prior to presentation and remained stable throughout the follow‐up period. The owner was unsure when the lesion appeared because they had not paid careful attention to see the skin under the hair coat. The lesion consisted of scattered, florid, ramified macules (Figure ), with mild dermatrophia and desquamation. The dog was otherwise healthy and there was no history of using drugs including flea and tick prevention treatments. 

Diagnostic procedure Clinical differential diagnoses included capillary haemangiomas, cutaneous vascular naevi, telangiectasia, cutaneous angiomatosis and secondary phenomena related to circulatory, coagulation, and endocrine disorders. Diascopy revealed a blanchable lesion. Dermoscopy was performed with Derma 9500 (Derma Medical Inc., Yokohama, Japan) combined with a PowerShot A630 camera (Canon Inc., Tokyo, Japan). The capillaries demonstrated a reticular appearance, and those in the superficial dermis showed dilation, different sizes and irregular linear or tortuous patterns in magnified views (Figure ). In contrast, the healthy skin did not show an erythematous colour change, and the capillaries appeared as thin red lines. Skin biopsy was performed with a 6‐mm biopsy punch under local anaesthesia; bleeding and purpura were not observed at either site after biopsy. Histopathological examination of the lesion revealed focal moderate dilation of the congested capillaries at the superficial dermis (Figure ). In addition, some of the vessels in the lower dermis and subcutaneous adipose tissue were mildly dilated. The dilated capillaries were lined by a single layer of uniform endothelial cells (Figure ). There were no obvious morphological abnormalities such as atypia or mitoses. In a biopsy of the healthy skin from over the left shoulder, capillary dilation was not observed. We performed Elastica van Gieson (EVG) staining, which showed as expected that the small, dilated capillaries lacked intimal elastic membrane (Figure ). Immunohistochemical staining using antibodies for alfa‐SMA (Mouse Monoclonal Antibody, Clone 1A4, 1:5000, SIGMA, USA) was also performed. It was shown that the dilated vessels, similar to the normal ones in the not affected skin, were surrounded by few positive cells interpreted as the pericytes (Figure ) (Alarcon‐Martinez et al. ; Nehls V et al, ). Based on the clinical and histopathological findings, an idiopathic cutaneous telangiectasia was diagnosed. 

Treatment and outcome The lesion was followed up over 3 years by regular medical checks without any treatments. The margin of the lesion expanded slightly, and the vasodilation appeared to be mildly accentuated (Figure ). However, the morphological pattern and distribution of lesions remained essentially the same as that of the original presentation, and the general condition was good during the follow‐up period. 

DISCUSSION We present a young dog with focal cutaneous telangiectasia based on clinical (including dermatoscopy) and histological features. Telangiectasia is defined as the permanent dilatation of pre‐existing blood vessels, creating small focal lesions, usually in the skin or mucous membranes (Demanuelle et al., ; Goldsmith et al., ). In this case, capillary haemangiomas, cutaneous vascular naevi, cutaneous angiomatosis and telangiectasias were clinically considered as the major clinical differential diagnosis. Capillary haemangiomas are typically blue to purple elevated lesions, characterised by the proliferation of blood‐filled vascular spaces lined with a single layer of well‐differentiated endothelial cells (Dompmartin et al. ; Gross et al. ). Cutaneous vascular naevi occur on the scrotum (synonyms: scrotal vascular hamartomas) and occasionally elsewhere in dogs (Muller et al., ; Sugai et al., ; Trappler et al., ). The lesions at the scrotum are characterised by single or multiple, slowly enlarging, hyperpigmented plaques (Trappler et al., ). Another report revealed a pink, red or purple flat lesion of variable size at the shoulder (Sugai et al., ). Histopathologically, the naevus and hamartoma are characterised by cavernous dilation and proliferation of blood vessels without atypia in the endothelial cells (Muller et al., ; Sugai et al., ; Trappler et al., ). Cutaneous angiomatosis manifests as dark red macules and patches, or may present as multiple plaques and nodules, and a tendency towards progression, including enlargement and invasion of the lesions (Affolter et al., ; Gross et al., ; Ide et al., ; Kim et al., ; Kuroki et al., ; Laganga et al., ; Olivieri et al., ; Peavy et al., ; Sluiter et al., ; Yager et al., ). Histopathologically, an infiltration pattern with well‐differentiated blood vessels extending into the underlying subcutaneous layers, can be observed. Two dogs with early age of onset angiomatosis, which did not show significant progression, were observed (Kim et al., ; Olivieri et al. ); both cases showed swelling or expanding lesions, and the histopathological examinations revealed an infiltrative pattern of well‐differentiated blood vessels in the superficial and deep dermis extending to the underlying subcutis. This case demonstrated non‐progressive focal dilation of capillaries at the superficial dermis, with lack of proliferation, inflammation and bleeding. The case is not suggestive of haemangioma, naevus and/or angiomatosis, as there was no apparent proliferation or malformation of the affected capillaries. It is suspected that the lesion appeared during the neonatal periods due to a non‐progressive nature in the dog. Primary telangiectasias have a good prognosis, with the exception of aesthetic considerations (Goldsmith et al., ; Küçük et al., ; Villela‐Segura, ). Cutaneous telangiectasia in dogs has been associated with Cushing's syndrome (Gross et al., ). As far as we know, there is only one published case with two areas of telangiectasia involving the right and left antebrachia in dogs (Demanuelle et al., ). The dog received anti‐inflammatory dosed glucocorticoids due to an allergic dermatitis only in the summer months for 7 years, but did not have them since a year before the skin lesion appeared. The cause of the telangiectasia in this dog could not be determined. There were no clinical or clinicopathological findings suggesting Cushing's syndrome in the present dog. Primary telangiectasia is included in the capillary malformation I category of simple human vascular malformations in the ISSVA . Several subtypes of telangiectasia have been discussed, and some of them may be reclassified in the future. Congenital unilateral naevoid telangiectasia (UNT) is presumably involved in the ISSVA  (Calonje et al., ; Goldsmith et al., ; Cossiolo et al., ; Küçük et al., ). It presents at birth or shortly after neonatal periods and is characterised by clustered telangiectasia with a reticular appearance that blanches with diascopy. Histopathologically, numerous dilated vessels are observed in the upper and middle dermis and, to a lesser extent, in the deeper part of the dermis in UNT. In our case, the rather young age of presentation of the lesion in our case may suggest a congenital disorder, and the clinical and histopathological findings were similar to those of UNT. Dermoscopy showed a reticulated appearance with tortuous vessels, which suggested dilated capillaries in the superficial layer of the dermis; these findings were also similar to the dermoscopic findings of UNT (Küçük et al., ; Villela‐Segura, ). Although dermoscopy is a useful non‐invasive tool for the examination of vascular lesions in humans, there are no reports on its use in animals for examining vascular lesions (Dong et al., ; Genovese et al., ; Scarampella et al., , ; Tomich et al., ; Zanna et al., , ). Despite anatomical differences in blood vessels of the skin between humans and dogs, we speculate that dermoscopy could be a valuable diagnostic tool for the identification and examination of vascular anomalies in dogs. Further studies are warranted to evaluate the usefulness of dermoscopic findings and the similarities of vascular anomalies including telangiectasia in humans and dogs; its utility in the development of a classification for canine vascular anomalies also requires further investigation. 

CONCLUSION This report describes the first young dog with idiopathic cutaneous telangiectasia that may resemble UNT in humans and may have a congenital origin. Dermoscopy was found to be a valuable tool for the examination of the vascular lesions in this case, and it may be applied for other vascular anomalies in dogs in the future. 

Ueyama, Akira : data curation; formal analysis; writing – original draft. Hoshino, Tomoya : formal analysis; supervision; writing – review & editing. Asakawa, Midori Goto : formal analysis; supervision; visualisation; writing – review & editing. Shimada, Toshio : resources; writing – review & editing. Nagata, Masahiko : conceptualisation; data curation; formal analysis; methodology; resources; supervision; validation; visualisation; writing – original draft; writing – review & editing. 

The authors have no conflicts of interest to declare. 

This study was self‐funded. 

The peer review history for this article is available at https://publons.com/publon/10.1002/vms3.940 

The authors confirm that the ethical policies of the journal, as noted on the journal's author guidelines page, have been adhered to. No ethical approval was required as this is a retrospective case report with no original research data. 

This case report was presented at the 2019 meeting of the Japanese Society of Veterinary Dermatology. 

