Sialoblastoma: a clinicopathologic and immunohistochemical study of 7 cases

Sialoblastomas With Solid Pattern Have FGFR2 Mutations and an Unfavorable Prognosis

Although sialoblastoma (SBL) is defined as a low-grade malignant salivary gland anlage neoplasm in the 2022 World Health Organization (WHO) Classification of Head and Neck Tumors, its histology, genetics, and behavior remain controversial due to the rarity of the tumor. Here, we performed the first comprehensive clinical, histologic, and molecular analyses of 8 SBLs to better understand their pathogenesis and prognosis. This cohort consisted of 5 boys and 3 girls, with ages ranging from birth to 9 years at diagnosis. Tumors occurred in the parotid (4), cheek (3), and submandibular glands (1). Histologically, 5 tumors primarily presented as a solid pattern consisting of primitive basaloid epithelial cells, often with necrosis. Three tumors exhibited a non-solid pattern, with 1 tumor mainly showing epithelial-myoepithelial carcinoma (EMC)-like histology, whereas the other 2 tumors exhibited basal cell adenoma (BCA)-like histology. All 5 solid SBLs harbored FGFR2 mutations, and 1 also harbored mutations in PALB2, AR, and MAP2K1. In contrast, non-solid pattern tumors were characterized by HRAS mutations or significant β-catenin nuclear positivity. All 5 solid tumors recurred, 3 of them developed distant metastases, and 2 died 40 and 44 months after diagnosis. Three non-solid tumors showed no evidence of disease recurrence at 49, 144, and 132 months, suggesting a relatively favorable prognosis. Overall, SBLs can be stratified into solid and non-solid patterns, with solid pattern tumors usually having FGFR2 mutations, increasing the risk of recurrence and metastasis. This stratification underscores the importance of genetic and morphologic profiling for predicting the prognosis of SBLs.

Infant with Parotid Sialoblastoma and Nevus Sebaceous, Treated with Surgery and Adjuvant Chemotherapy

Sialoblastoma is an extremely rare embryonal tumor derived from salivary gland primordial cells. Treatment usually consists of surgery alone; however, in some cases, chemotherapy is required and is administered with good response. We present a case of a 5-week-old girl diagnosed with a parotid gland tumor and co-existing nevus sebaceous on the face. Initial tumorectomy was microscopically non-radical and histopathology revealed sialoblastoma. The patient received adjuvant chemotherapy consisting of vincristine, actinomycin, and cyclophosphamide. Due to imaging studies being inconclusive regarding response and possible residual disease, a second surgery (total parotidectomy) was performed. The histopathology results showed fields of necrosis in the parotid gland but no neoplastic cells in the material. The patient remains under watchful observation and there is no evidence of relapse 12 months after the second surgery. The adjuvant chemotherapy regimen with vincristine, actinomycin, and cyclophosphamide is a viable option of treatment in children with sialoblastoma.

The Cellular and Molecular Landscape of Synchronous Pediatric Sialoblastoma and Hepatoblastoma

Sialoblastoma (SBL) is an infrequent embryonal malignant tumor originating from the salivary gland, resembling primitive salivary gland anlage, whereas hepatoblastoma (HB) is the most common pediatric liver malignancy. The simultaneous occurrence of both tumors is extremely rare. Here we reported a case of a 6-month-old infant diagnosed with synchronous SBL and HB. The patient received neoadjuvant chemotherapy followed by surgical resection. Fresh tissues of both tumors were collected before and after chemotherapy, which were further profiled by whole exome sequencing (WES) and single-cell RNA sequencing (scRNA-seq). WES analysis revealed potential somatic driver mutation PIK3CA p.Glu454Lys for SBL and canonical mutation CTNNB1 p.Ser45Pro for HB. No shared somatic variants or common copy number alterations were found between SBL and HB primary tumor samples. Though scRNA-seq, single-cell atlases were constructed for both tumors. SBL may recapitulate a pre-acinar stage in the development of salivary gland, including basaloid, duct-like, myoepithelial-like, and cycling phenotypes. In the meantime, HB was composed of tumor cells resembling different stages of the liver, including hepatocyte-like, hepatic progenitor-like, and hepatoblast-like cells. After chemotherapy, both tumors were induced into a more mature phenotype. In terms of transcriptional signatures, SBL and HB showed enhanced expression of epithelial markers KRT8, KRT18, and essential embryo development genes SDC1, MDK, indicating the disruption of normal embryo epithelium development. Finally, heterozygous deleterious germline mutation BLM and FANCI were identified which could predispose the patient to higher cancer risk. It partially explained the reason for the co-occurrence of SBL and HB. Taken together, we provided valuable resources for deciphering cellular heterogeneity and adaptive change of tumor cells after chemotherapy for synchronous SBL and HB, providing insights into the mechanisms leading to synchronous pediatric tumors.

Two Synchronous Neonatal Tumors: An Extremely Rare Case

We report a case of a newborn with two synchronous tumors-sialoblastoma and hepatoblastoma-diagnosed at 20 weeks of gestation by magnetic resonance imaging (MRI) and ultrasonography (US). The aim of this study was to describe the management of this case together with a review of the literature. Our patient had a large facial tumor associated with extremely high alpha-fetoprotein levels. Diagnosis of the tumors was made by surgical biopsy, showing typical features in both. Sialoblastoma is a potentially aggressive tumor. In our case, the Ki67 index in the sialoblastoma was between 20 and 30%, indicating a possibly unfavorable behavior. The infant underwent surgery and chemotherapy in different steps. Complete surgical resection with clean margins is considered to be the best treatment option for sialoblastoma. Only four similar cases were previously reported. Timely management by a multidisciplinary team is essential in these difficult cases. In our patient, outcome was good at the time of this report.

[Pediatric salivary gland tumors and tumor-like lesions]

Salivary gland tumors and tumor-like lesions in the pediatric population are uncommon. They comprise a heterogeneous group of infectious/inflammatory and neoplastic conditions. Pediatric salivary neoplasms include benign tumors of mesenchymal or epithelial origin as well as malignancies of epithelial (carcinomas), mesenchymal (sarcoma) or hematolymphoid (lymphoma) derivation. Infectious/inflammatory conditions and hematolymphoid malignancies may represent either genuine parenchymal pathology or conditions involving intraglandular lymph nodes of the parotid glands (intraglandular lymphadenopathy and intraglandular nodal lymphomas). Pediatric sialadenitis may be of diverse etiologies including viral (mumps, CMV, HIV, etc.), bacterial, autoimmune (juvenile Sjögren syndrome) or idiopathic (chronic recurrent juvenile sialectatic sialadenitis). Angiomatous lesions (juvenile capillary hemangioma, lymphangioma and vascular malformation) and pleomorphic adenomas represent the most common pediatric benign mesenchymal and benign epithelial tumors, respectively. The vast majority of salivary gland carcinomas in children and adolescents represent low-grade mucoepidermoid carcinomas followed by acinic cell and adenoid cystic carcinomas (together >80% of carcinomas). Other malignant neoplasms include (rhabdomyo-) sarcomas, malignant lymphomas and very rarely sialoblastomas. This long differential diagnosis list of etiologically and biologically highly heterogeneous entities, their shared clinical presentation as "salivary gland enlargement" and the significant differences in their therapeutic strategies and prognosis underline the need for careful assessment to identify the correct diagnosis. Diagnosis is mainly based on a set of typical clinical and imaging features, serological/microbiological findings and, in selected cases, histomorphological characteristics in biopsy specimens.

Sialoblastoma in chin and management of treatment

OBJECTIVE

Sialoblastoma is a rare salivary gland tumor mainly located in parotid. In this article, we aimed to review the clinical manifestations and treatments of sialoblastoma, especially to provide effective chemotherapy regimens to instruct internal medicine therapy for unresectable or recurrent tumors.

METHOD

We reported a 1-year old girl who presented a left-sided firm facial mass and subsequently diagnosed as sialoblastoma. Afterwards, we reviewed and analyzed relevant literatures.

RESULTS

Sixty-four cases of pediatric sialoblastoma were reviewed. Of them, surgical excision was the basic treatment, 17 cases received chemotherapy, and 15 cases got good response. Lung metastasis was reported in six patients, all of whom had good response to chemotherapy.

CONCLUSION

Chemotherapy may play an important role in residual, extensive, metastatic and relapsed cases. In addition, lung metastasis was unlikely to exert a significant effect on prognosis.

Pediatric sialoblastoma: Evaluation and management

OBJECTIVES

Sialoblastoma is a rare congenital salivary gland tumor of epithelial origin. The objectives of this study are to review the literature regarding clinical presentation of sialoblastoma, evaluate the effectiveness of various treatment methods, and present guidelines for evaluation and management in the pediatric population.

DATA SOURCES

Case presentation and literature review.

REVIEW METHODS

A comprehensive search was conducted to identify cases of pediatric sialoblastoma in the English-language literature. The presentation, evaluation, and management of reported cases were analyzed. We also report an invasive and recurrent case in a pediatric patient to highlight the aggressive nature of these lesions.

RESULTS

Sixty-two cases of pediatric sialoblastoma were reviewed. The age at initial presentation ranged from before birth to 15 years. The parotid gland was the most common location (n = 47). Surgical excision was the primary treatment in all patients. Nine patients developed metastatic disease of the lung, lymph nodes, or bone. Almost a third of patients had recurrence and over two thirds of patients were tumor-free for at least 1 year following their last treatment intervention.

CONCLUSION

Prompt and complete surgical excision should be recommended to prevent local and systemic recurrence of pediatric sialoblastoma. Chemotherapy has also shown promise in several cases, and clinical genomics may shed light on more therapy options. Patients should be closely followed for at least 12 months following diagnosis, or longer depending on the histopathological staging of the tumor.

Sialoblastoma of the cheek: A case report and review of the literature

Sialoblastoma is a rare salivary gland tumor that recapitulates the primitive salivary gland anlage. The authors herein report a case of sialoblastoma of a minor salivary gland, clinically presenting with progressive enlargement of a mass in the cheek of a 1-year-old female infant. Histopathologically, the mass consisted of tight clusters of basaloid cells and partially formed ductal and pseudo-ductal spaces separated by thin fibrous bands. Immunohistchemical studies demonstrated the presence of cytokeratin AE1/AE3, p63, CD99, α-fetoprotein (AFP) and Hep Par-1 expression in a considerable number of tumor cells. The clinical and pathological characteristics are presented and relevant literature is reviewed. Early complete surgical excision is recommended for the treatment of sialoblastoma. Radiation may be considered in cases with incomplete resection of the tumor. Chemotherapy may play a vital role in extensive, metastatic, or relapsed cases, or in cases with inadequate excision. The follow-up treatment should be frequent and prolonged. To the best of our knowledge, this is the first reported case of sialoblastoma of the cheek with immunoreactivity for AFP and Hep Par-1, which may be associated with the embryonic origin of the tumor. AFP may be a useful marker of tumor response in patient with sialoblastoma.

Disorders and tumors of the salivary glands in children

Salivary gland neoplasms are rare in children. In infants most tumors are benign hemangiomas, with some notable exceptions, such as sialoblastomas. An asymptomatic swelling in the periauricular region is the most common presenting complaint in older children. Approximately 50% of these lesions are malignant, which dictates a thorough diagnostic evaluation by a head and neck surgeon. Surgical excision is the primary treatment modality. Prognosis is primarily determined by histopathologic findings. This review discusses neoplastic lesions of the salivary glands in children, and malignant epithelial tumors in particular.

Sialoblastoma of the parotid gland in a 13-year-old girl with multiple recurrences and long-term follow-up

BACKGROUND

Sialoblastoma is an extremely rare congenital salivary gland tumor of epithelial origin. It is usually localized in the parotid or submandibular gland and presents primarily at birth or in early childhood.

METHODS

We report a case of a 13-year-old girl with a sialoblastoma of the parotid gland presenting as an asymptomatic painless mass.

RESULTS

The patient showed multiple recurrences and, based on the histopathological finding of facial nerve infiltration, was treated surgically with total parotidectomy and facial nerve reconstruction.

CONCLUSION

Because of the rare occurrence of sialoblastoma, there is no evidence-based treatment of choice. The treatment should be individualized, taking into consideration the patient's age, the high locoregional recurrence rate, the local aggressive characteristics, and the potential metastatic activity of this rare tumor. A close follow-up of the patient is strongly recommended.

Salivary gland diseases in children

Salivary gland diseases in children are rare, apart from viral-induced diseases. Nevertheless, it is essential for the otolaryngologist to recognize these uncommon findings in children and adolescents and to diagnose and initiate the proper treatment.

The present work provides an overview of the entire spectrum of congenital and acquired diseases of the salivary glands in childhood and adolescence. The current literature was reviewed and the results discussed and summarized.

Besides congenital diseases of the salivary glands in children, the main etiologies of viral and bacterial infections, autoimmune diseases and tumors of the salivary glands were considered. In addition to the known facts, new developments in diagnostics, imaging and therapy, including sialendoscopy in obstructive diseases and chronic recurrent juvenile sialadenitis were taken into account. In addition, systemic causes of salivary gland swelling and the treatment of sialorrhoea were discussed. Although salivary gland diseases in children are usually included in the pathology of the adult, they differ in their incidence and some­times in their symptoms. Clinical diagnostics and especially the surgical treatment are influenced by a stringent indications and a less invasive strategy. Due to the rarity of tumors of the salivary glands in children, it is recommended to treat them in a specialized center with greater surgical experience.

Altogether the knowledge of the differential diagnoses in salivary gland diseases in children is important for otolaryngologists, to indicate the proper therapeutic approach.

Sialoblastoma: A literature review from 1966-2011

Sialoblastoma is a rare congenital tumour of the salivary glands arising mainly from the parotid gland. It is usually diagnosed at birth or shortly thereafter with a significant variability in histological appearance and clinical course. In extensive search of PubMed indexed journals, we got 46 cases of "sialobalstoma/embryoma/congenital basal adenoma", with one case was of German literature and three additional cases of adult sialobalstoma. This article has extensively reviewed the clinical, histopathological and immunohistochemical features, Magnetic resonance imaging (MRI) and Computerized Tomography (CT) findings, treatment and prognosis.

Sialoblastoma- long-term follow-up and remission for a rare salivary malignancy

Sialoblastoma is a rare salivary neoplasm which presents either congenitally or during early infancy. It was originally considered a benign neoplasm, however a number of reported cases have documented locoregional recurrence and distant metastases. Currently, there is no consensus on the appropriate treatment for this neoplasm. We report on long term follow-up of a patient with metastatic sialoblastoma, and a brief discussion of the possible treatment modalities currently being considered.

Congenital minor salivary gland sialoblastoma: a case report and review of the literature

Sialoblastoma is the most common epithelial tumor of the salivary gland. We report a case of congenital sialoblastoma arising in a minor salivary gland of the buccal mucosa of a male infant. After radiologic evaluation, an incisional biopsy was performed and then the mass was excised en bloc. Histologic features were both favorable and unfavorable. However, there was no recurrence for 5 months. In spite of a reported histologic grading system, the clinical course of isolated sialoblastoma is considered unpredictable. More published case reports of this rare tumor may enable histologic and clinical correlation in order to accurately predict prognosis.

Management of sialoblastoma with surgery and brachytherapy

Sialoblastoma is a rare congenital or perinatal salivary gland tumor with significant variability in histological appearance and biological behavior. We reported one case of sialoblastoma occurring in the parotid gland of an 18-month-old female. The tumor was excised with negative margins, and the sacrificed facial nerve was reconstructed with great auricular nerve graft. The tumor recurred 6 months after operation and was treated with (125)I seed implant brachytherapy. No recurrence was found after 21 months of follow-up.

Sialoblastoma of salivary glands in children: chemotherapy should be discussed as an alternative to mutilating surgery

Sialoblastoma is a very rare congenital salivary gland tumor. No consensus has been reached concerning the treatment of this tumor due to its rarity. The treatment of reference is surgery, which can be mutilating, in the case of a locally invasive tumor. The treatment of metastatic disease is also controversial. The authors report a new case of a 6-year-old girl with a progressively growing left parotid mass since birth. The first cytological diagnosis was that of pleomorphic adenoma. Due to local progression, superficial parotidectomy was performed at the age of 3.5 years and revealed a diagnosis of sialoblastoma. Six months later, local recurrence and lung metastasis were treated by neoadjuvant chemotherapy with a very good partial response on the local recurrence and the lung metastasis, allowing complete parotidectomy with sacrifice of the facial nerve. Bilateral lung biopsies after adjuvant chemotherapy showed total necrosis. No recurrence was observed with a follow-up of 1 year. This case and a review of the literature confirm the very good chemosensitivity of this tumor and argue in favor of neoadjuvant chemotherapy for locally invasive tumors rather than extensive mutilating surgery.

Sialoblastoma: utility of Ki-67 and p53 as a prognostic tool and review of literature

Sialoblastoma is a rare tumor of the salivary gland that commonly occurs in the parotid gland and occasionally in the sub-mandibular gland. The malignant potential of sialoblastoma has been documented in only 3 of 32 cases of sialoblastoma reported thus far. In the last 15 years, we have encountered 2 cases of sialoblastoma, in a newborn and in a 15-year-old boy, both arising within the parotid gland. Case 1 has been previously reported and although there were 2 recurrences, at 1 and 9 years post resection, it has shown benign biological behavior. Case 2 is unusual since the patient presented with metastases. We reviewed the 2 cases, including the 2 recurrences from the first case, for histologic and immunohistochemical differences. Although both cases showed similar cytomorphologic features, there was a significant difference in Ki-67 expression: 20% in case 1 (original tumor), <2% in case 1 (recurrent tumor), and nearly 70-80% in the recent malignant case. The difference is remarkable when combined with p53 expression, which was focally positive in the first case but diffusely positive in the second. This report highlights the potential utility of proliferation markers such as Ki-67 in concert with p53 expression to better predict the biological behavior of a rare but locally aggressive neoplasm.

Sialoblastoma in adults: distinction from adenoid cystic carcinoma

Essentially, sialoblastoma is a disease of infancy with the oldest case presenting at 4 years of age. About one third of pediatric sialoblastoma cases will have a cribriform growth pattern. No adult cases have been reported with a specific diagnosis of sialoblastoma. If even focal cribriforming were present, such cases have undoubtedly been diagnosed as adenoid cystic carcinoma. Such was the circumstance in the 3 adult tumors presented in this report. Each case, however, has the primitive histopathology with discrete nests of basaloid tumor cells, associated bilayered ductal structures and the fibromyxoid stroma characteristic for sialoblastoma with its resemblance to fetal salivary gland or salivary gland with arrested development. One key example has 28-year follow-up. Sialoblastoma, whether in a child or adult with or without a cribriform growth pattern, appears to have a more favorable prognosis than adenoid cystic carcinoma. Aspects of the histological differential diagnosis of these 2 tumors are discussed.

Selective pathologies of the head and neck in children: a developmental perspective

The range of pathology seen in the head and neck region is truly amazing and to a large extent probably mirrors the complex signaling pathways and careful orchestration of events that occurs between the primordial germ layers during the development of this region. As is true in general for the entire discipline of pediatric pathology, the head and neck pathology within this age group is as diverse and different as its adult counterpart. Cases that come across the pediatric head and neck surgical pathology bench are more heavily weighted toward developmental and congenital lesions such as branchial cleft anomalies, thyroglossal duct cysts, ectopias, heterotopias, choristomas, and primitive tumors. Many congenital "benign" lesions can cause significant morbidity and even mortality if they compress the airway or other vital structures. Exciting investigations into the molecular embryology of craniofacial development have begun to shed light on the pathogenesis of craniofacial developmental lesions and syndromes. Much more investigation is needed, however, to intertwine aberrations in the molecular ontogeny and development of the head and neck regions to the represented pathology. This review will integrate traditional morphologic embryology with some of the recent advances in the molecular pathways of head and neck development followed by a discussion of a variety of developmental lesions finishing with tumors presumed to be derived from pluripotent/progenitor cells and tumors that show anomalous or aborted development.

What's new in the AFIP fascicle on salivary gland tumors: a few highlights from the 4th Series Atlas

After a 12 year interval from the previous fascicle, a new fascicle on Tumors of the Salivary Glands in the new fourth series of the AFIP Atlas of Tumor Pathology was published in 2008. The data, presentation, illustrations, tables, and physical characteristics of the newest fascicle have been updated and improved. There have only been a few alterations and additions to the classification of tumors and tumor-like non-neoplastic conditions of salivary gland. Three of the most significant are discussed in this paper. Sialoblastoma has been reclassified as malignant; inflammatory pseudotumor has been reclassified as neoplastic and re-identified as inflammatory myofibroblastic tumor; and sclerosing polycystic adenosis is a new entity among tumor-like conditions.

Sialoblastoma

Sialoblastoma should be considered in the diagnosis of a perinatal neck swelling that appears to be contiguous with the submandibular salivary gland. These are exceedingly rare perinatal salivary tumors of epithelial origin with variable biologic behavior including the potential for local and systemic recurrence. We report the case of a 3-month-old boy who presented with a submandibular swelling of insidious onset that was initially thought to be a lymph node enlargement.

Sialoblastoma arising in ectopic salivary gland tissue

Sialoblastoma is a rare, congenital or perinatal tumour predominately affecting the parotid or submandibular salivary glands. We report a case of sialoblastoma arising in ectopic salivary gland tissue in the anterior cheek of a female infant. This lesion clinically and on ultrasound mimicked a haemangioma. Following imaging and tissue diagnosis, the lesion was surgically excised with clear margins. The patient remained disease free at 6 months follow up.