This article summarizes the current status and research advances in the diagnosis and treatment of pediatric skin tumors and vascular malformations, with particular emphasis on the pathogenesis, clinical manifestations, diagnostic approaches, and therapeutic options for hemangiomas, vascular malformations, histiocytosis, mastocytosis, and mycosis fungoides. With the enhanced understanding of distinctive growth and regression patterns of pediatric skin tumors, therapeutic strategies have been progressively optimized. However, significant challenges persist in managing pediatric skin neoplasms. Future investigations should prioritize the establishment of pediatric-specific molecular diagnostic and therapeutic systems, and integrate precision medicine with individualized strategies, so as to improve clinical outcomes and quality of life in affected children.

Objective:To delineate clinical characteristics of infantile myofibroma/myofibromatosis (IM) .Methods:A retrospective analysis was conducted on histologically confirmed IM cases from Beijing Children's Hospital, Henan Children's Hospital, and Maternity and Child Health Care of Guangxi Zhuang Autonomous Region between August 2014 and July 2021. The clinical, pathological, imaging features, and outcomes were analyzed and summarized.Results:A total of 44 IM patients were included, comprising 28 males (63.6%) and 16 females (36.4%). Their ages at onset ( M[ Q1, Q3]) were 14.8 (4.7, 42.4) months, and 26 patients (59.1%) developed IM before the age of 1 year. Seven patients (15.9%) were initially diagnosed with IM. Skin involvement occurred in 42 patients (95.5%), of whom 30 (71.4%) presented with a solitary lesion and 12 (28.6%) with multiple lesions. Skin lesions mainly manifested as painless, firm nodules or masses. The most commonly involved extracutaneous site was the skeletal system (21/44, 47.7%). Histopathological examination of all 44 IM cases revealed a biphasic architecture pattern, characterized by the coexistence of two distinct morphologies or cell types within the tumor tissues (including spindle cell areas composed of fascicularly and densely arranged myofibroblasts, and primitive mesenchymal cell areas composed of small, round undifferentiated cells. Immunohistochemical study was performed in 42 cases; 40 (95.2%) were positive for smooth muscle actin, and 20 (47.6%) were positive for CD34. Genetic testing was conducted in 3 cases, and NOTCH mutations were identified in 2. Among the 44 patients, 30 patients (68.2%) underwent surgical excision, 5 patients (11.4%) received intralesional injections of triamcinolone acetonide, 1 patient (2.3%) received chemotherapy for intestinal involvement, and 8 patients were managed expectantly. During the follow-up of 49 (36, 60) months, lesions completely resolved in 42 cases (95.5%), while 2 cases died of pulmonary infection following chemotherapy or postoperative airway compression. Conclusions:IM predominantly affected infants and young children, with the skin and skeletal system being the most commonly involved sites. Skin lesions often manifested as firm nodules or masses, and histopathological examination was crucial for definitive diagnoses. Most IM cases exhibited favorable outcomes.

This article summarizes the current status and research advances in the diagnosis and treatment of pediatric skin tumors and vascular malformations, with particular emphasis on the pathogenesis, clinical manifestations, diagnostic approaches, and therapeutic options for hemangiomas, vascular malformations, histiocytosis, mastocytosis, and mycosis fungoides. With the enhanced understanding of distinctive growth and regression patterns of pediatric skin tumors, therapeutic strategies have been progressively optimized. However, significant challenges persist in managing pediatric skin neoplasms. Future investigations should prioritize the establishment of pediatric-specific molecular diagnostic and therapeutic systems, and integrate precision medicine with individualized strategies, so as to improve clinical outcomes and quality of life in affected children.

Objective:To delineate clinical characteristics of infantile myofibroma/myofibromatosis (IM) .Methods:A retrospective analysis was conducted on histologically confirmed IM cases from Beijing Children's Hospital, Henan Children's Hospital, and Maternity and Child Health Care of Guangxi Zhuang Autonomous Region between August 2014 and July 2021. The clinical, pathological, imaging features, and outcomes were analyzed and summarized.Results:A total of 44 IM patients were included, comprising 28 males (63.6%) and 16 females (36.4%). Their ages at onset ( M[ Q1, Q3]) were 14.8 (4.7, 42.4) months, and 26 patients (59.1%) developed IM before the age of 1 year. Seven patients (15.9%) were initially diagnosed with IM. Skin involvement occurred in 42 patients (95.5%), of whom 30 (71.4%) presented with a solitary lesion and 12 (28.6%) with multiple lesions. Skin lesions mainly manifested as painless, firm nodules or masses. The most commonly involved extracutaneous site was the skeletal system (21/44, 47.7%). Histopathological examination of all 44 IM cases revealed a biphasic architecture pattern, characterized by the coexistence of two distinct morphologies or cell types within the tumor tissues (including spindle cell areas composed of fascicularly and densely arranged myofibroblasts, and primitive mesenchymal cell areas composed of small, round undifferentiated cells. Immunohistochemical study was performed in 42 cases; 40 (95.2%) were positive for smooth muscle actin, and 20 (47.6%) were positive for CD34. Genetic testing was conducted in 3 cases, and NOTCH mutations were identified in 2. Among the 44 patients, 30 patients (68.2%) underwent surgical excision, 5 patients (11.4%) received intralesional injections of triamcinolone acetonide, 1 patient (2.3%) received chemotherapy for intestinal involvement, and 8 patients were managed expectantly. During the follow-up of 49 (36, 60) months, lesions completely resolved in 42 cases (95.5%), while 2 cases died of pulmonary infection following chemotherapy or postoperative airway compression. Conclusions:IM predominantly affected infants and young children, with the skin and skeletal system being the most commonly involved sites. Skin lesions often manifested as firm nodules or masses, and histopathological examination was crucial for definitive diagnoses. Most IM cases exhibited favorable outcomes.

A 3-year-6-month-old boy presented with multiple asymptomatic banded white macules at birth, which expanded in proportion to his body, and deformity of his right thumb with slight dyskinesia. The patient showed difficulty in communication and concentration compared with children of the same age. The family history was unremarkable. The child had clear consciousness, passable spirits, and poor language ability. Physical examination revealed a special face and slight macrodactyly of the right thumb joints, and the heart, lung, and abdominal examination was otherwise normal. Skin examination showed multiple banded or confluent irregular white macules of varying sizes and slightly elevated plaques distributed along the Blaschko′s lines on the right chest, the flexor aspect of the right upper limb, the median line of the lower abdomen, and the right lower limbs, and banded brown macules on the palmar side of the right hand and radial aspect of the right thumb. Histopathological findings of the while macule on the lower limb were consistent with basaloid follicular hamartoma. Cranial magnetic resonance imaging revealed agenesis of the corpus callosum. Whole-exome sequencing of the lesional tissue showed a mutation c.1234C>T (p.L412F) in the SMO gene, which was not found in his parents. A diagnosis of Curry-Jones syndrome was made based on the skin lesions, and pathological and genetic findings. The mutation c.1234C>T (p.L412F) in the SMO gene may contribute to the disease. The patient continued functional exercises to improve the mobility of his right thumb, and underwent a close follow-up.

Objective:To analyze gene mutations in and clinical phenotypes of 4 children with recessive dystrophic epidermolysis bullosa (RDEB) .Methods:Clinical data were collected from 4 children with RDEB, and DNA was extracted from peripheral blood samples of the children and their parents. A multi-gene panel targeting congenital epidermolysis bullosa was used for high-throughput sequencing. After identification of causative gene mutations, Sanger sequencing was performed to bidirectionally verify the mutations in the patients and their parents.Results:Genetic testing showed 8 compound heterozygous mutations in the COL7A1 gene in the 4 cases. Case 1 was diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.7828C>T and a maternal mutation c.448G> A; case 2 was also diagnosed with moderate generalized RDEB, and inherited a paternal mutation c.3625_3635del and a maternal mutation c.2726_2728del; case 3 was diagnosed with localized RDEB, carrying a paternal mutation c.682+1G>A and an allelic mutation c.5532+1G>A, but the mutation c.5532+1G>A was not identified in the DNA extracted from the parental peripheral blood samples; case 4 was diagnosed with severe generalized RDEB, and inherited a paternal mutation c.5196delC and a maternal mutation c.500_501insAGGG. Among these mutations, c.2726_2728del and c.5196delC had not been reported previously.Conclusions:All the 4 children with RDEB carried compound heterozygous mutations in the COL7A1 gene, which may be the cause of RDEB. The phenotypes of biallelic frameshift mutation carriers appearred more severe than those of carriers of compound heterozygous mutations composed of biallelic splice site, missense and nonsense, frameshift and amino acid deletion or insertion mutations.

Objective:To investigate clinical manifestations and histopathological features of and surgical timing for cerebriform sebaceous nevus.Methods:Clinical data were collected from 14 children with cerebriform sebaceous nevus in Beijing Children′s Hospital from June 2014 to December 2019, and clinical manifestations, histopathological features and surgical timing were analyzed retrospectively.Results:Of the 14 children, 10 were males and 4 were females. They presented with skin lesions at birth, which were solitary and located on the head and face. These skin lesions gave a cerebriform appearance, with an average diameter of 4.79 cm. Systemic examination showed no abnormality in any children. Histopathological examination showed obvious papillomatous epidermal hyperplasia, large number of mature sebaceous glands and immature hair follicles. The 14 children underwent surgeries at an average age of 1.94 years. No recurrence was observed during the follow-up of 6 months to 6 years after surgery.Conclusion:Cerebriform sebaceous nevus is characterized by a unique cerebriform appearance, mostly occurs on the head and face, and is liable to attract attention, which usually leads to an earlier surgical selection.

Objective To investigate clinical manifestations,pathological features and outcomes of primary osteoma cutis in children.Methods Eleven children with confirmed primary osteoma cutis diagnosed in Department of Dermatology,Beijing Children's Hospital between 2011 and 2018 were included into this study.The clinical manifestations,histopathological features,and outcomes were analyzed retrospectively.Results Among the 11 patients,7 were males and 4 were females.Primary osteoma cutis occurred within 22 months after birth in all the children,the median age of onset was 1 month,and the disease occurred during the first 6 months of life in 10 children.The skin lesions were characterized by skincolored or reddish indurated papules,plaques or nodules of varying size with slight epidermal atrophy.Three patients had local skin lesions,and 8 had multiple skin lesions.Serum calcium and parathyroid hormone levels were within normal limits in all the children,and no developmental deformity was observed at birth in any of the children.Histopathological examination revealed the formation of mature lamellar bone in the dermis in all the cases,which involved the subcutaneous adipose tissue in 5 cases.The skin lesions became stable 8-18 months after the occurrence in 10 patients,which was consistent with primary plaquelike osteoma cutis.Only 1 patient underwent a slowly progressive course,and the skin lesions involved subcutaneous deep tissues,leading to dyskinesia,which was consistent with progressive osseous heteroplasia.Conclusions Primary osteoma cutis in children mostly occurs in infancy,whose clinical manifestations are atrophic,indurated plaques or nodules,and its main pathological feature is the formation of mature lamellar bone.Long-term follow-up is needed,and attention should be paid to the occurrence of progressive osseous heteroplasia.

Objective To analyze the clinical and pathological features of childhood bullous pilomatricoma.Methods The clinical and pathological features were analyzed in 16 patients with bullous pilomatricoma,who visited Department of Dermatology of Beijing Children's Hospital from 2013 to 2017.Results Among the 16 patients,5 were males,and 11 were females.Their age of onset ranged from 4 months to 11 years,and the median age of onset was 8.5 years.Their course of disease ranged from 2 months to 4 years,and the average course of disease was 10 months.The tumors were found predominantly on the upper limbs (10 cases,including 7 on the upper arm,2 on the shoulder and 1 on the forearm),followed by the face (4 cases) and the neck (2 cases).These tumors manifested as limited pushable red lumps with blister-like appearance,and telangiectasia was observed on the surface of some lesions.The diameters of the lumps ranged from 0.5 cm to 3 cm,and hard nodules could be detected in the blisters by palpation.Under dermoscopy,uniform red background was observed in 16 cases,unstructured white area in 13,unstructured blue-grey area in 4,and liner or irregular branched vessels.Two or more dermoscopic features were observed in 15 patients.All the skin lesions were resected by surgery,and no recurrence was observed during the follow-up of 1-5 years.Histopathological examination showed that the tumors were located in the middle to deep dennis,and mainly consisted of basaloid cells and shadow cells,as well as transitional cells between the above two kinds of cells.Varying degrees of infiltration of inflammatory cells and hyperplasia and calcification of the fibrous connective tissue were observed in the tumor interstitium,with multinucleated giant cells in some areas.There were varying degrees of infiltration of inflammatory ceils,lymphangiectasis,reduction or absence of elastic fibers in the dennis between the epidermis and tumors.Conclusions Childhood bullous pilomatricoma mostly occurs on the upper limbs,face and neck.Histopathologically,the tumor consists of basaloid cells and shadow cells with lymphangiectasis and reduction of elastic fibers in the dermis.The main dermoscopic features are red background and unstructured white areas.Its prognosis is good after surgical excision.

Objective To investigate clinical characteristics of tuberous sclerosis(TSC)without nervous system abnormalities in infants. Methods Clinical manifestations of 12 infants with TSC were analyzed. Reflectance confocal microscopy (RCM)was performed in 5 of the 12 infants. Two patients underwent histopathological examination and electron microscopic examination. Results The age at first clinic visit for TSC ranged from 2 to 18 months (median, 8.6 months)among these patients. Before occurrence of nervous symptom, TSC mainly manifested as hypomelanotic macules, nodules in the subependymal layer or walls of lateral ventricles of the brain, cardiac rhabdomyoma and multiple renal cysts. RCM revealed intact dermal papillary rings with low reflectivity and obscure boundaries in 5 infants. Histopathological examination showed a local decrease in melanocytes and pigment granules in basal cells. Electron microscopic examination showed a normal number of melanin granules in the cytoplasm of melanocytes in the basal layer. Conclusions Before appearance of nervous system abnormalities, TSC mainly manifests as hypomelanotic macules in infants, and is easily confused with vitiligo in clinic. RCM examination may serve as a useful method to distinguish infant TSC from hypopigmented diseases.