Nasal chondromesenchymal hamartoma in children with pleuropulmonary blastoma--A report from the International Pleuropulmonary Blastoma Registry registry

Estrogen Receptor Expression in DICER1-related Lesions is Associated With the Presence of Cystic Components

DICER1 tumor predisposition syndrome results from pathogenic variants in DICER1 and is associated with a variety of benign and malignant lesions, typically involving kidney, lung, and female reproductive system. Over 70% of sarcomas in DICER1 tumor predisposition syndrome occur in females. Notably, pediatric cystic nephroma (pCN), a classic DICER1 tumor predisposition syndrome lesion, shows estrogen receptor (ER) expression in stromal cells. There are also renal, hepatic, and pancreatic lesions unassociated with DICER1 tumor predisposition syndrome that have an adult female predominance and are characterized/defined by ER-positive stromal cells. Except for pCN, the expression of ER in DICER1-associated lesions remains uninvestigated. In the present study, ER expression was assessed by immunohistochemistry in 89 cases of DICER1-related lesions and 44 lesions lacking DICER1 pathogenic variants. Expression was seen in stromal cells in pCN and pleuropulmonary blastoma (PPB) types I and Ir, whereas anaplastic sarcoma of kidney and PPB types II and III were typically negative, as were other solid tumors of non-Müllerian origin. ER expression was unrelated to the sex or age of the patient. Expression of ER showed an inverse relationship to preferentially expressed antigen in melanoma (PRAME) expression; as lesions progressed from cystic to solid (pCN/anaplastic sarcoma of kidney, and PPB types I to III), ER expression was lost and (PRAME) expression increased. Thus, in DICER1 tumor predisposition syndrome, there is no evidence that non-Müllerian tumors are hormonally driven and antiestrogen therapy is not predicted to be beneficial. Lesions not associated with DICER1 pathogenic variants also showed ER-positive stromal cells, including cystic pulmonary airway malformations, cystic renal dysplasia, and simple renal cysts in adult kidneys. ER expression in stromal cells is not a feature of DICER1 perturbation but rather is related to the presence of cystic components.

Pathogenic Somatic Mutation of DICER1 and Clinicopathological Features in Nasal Chondromesenchymal Hamartomas: A Series of Nine Cases

Nasal chondromesenchymal hamartoma (NCMH) is a rare benign polypoid mesenchymal tumor arising in the nasal cavity and/or paranasal sinuses. Recognizing these sporadic, rare lesions is crucial, as surgical complete removal of the mass is the common treatment approach. This retrospective study analyzed the demographics, symptoms, and imaging data of 9 patients diagnosed with NCMH between January 2017 and June 2023, possibly representing the largest single-center adult case cohort to date. Diagnostic techniques included nasal endoscopy, CT/MRI scan, immunohistological studies, and morphologic comparisons. Pathologic specimens were subjected to Sanger sequencing of exons 24 and 25 of DICER1. The average age of 9 cases was 24.4 years, and the oldest was 55 years. Four of the patients were children, ranging from 1 year old to 11 years old, with an average of 4.5 years. Nasal congestion is the most common registered symptom. Endoscopic findings showed that most patients had smooth pink neoplasms or polypoid masses in the nasal meatus. Radiologic scanning revealed soft-tissue density masses that occupied the nasal cavity. Histologically, the characteristic structure of NCMHs is immature cellular cartilage nodules and mature cartilage nodules distributed in a loose mucoid matrix. Five of the 9 patients had somatic DICER1 missense mutations. Four of the patients with DICER1-mutated NCMH exhibited a p.E1813 missense hotspot mutation. We also report a case of a rare p.P1836H missense mutation. The detected DICER1 somatic mutations provide compelling evidence of an association with the DICER1 tumor family. We emphasize the importance of pathologic consultation and the need for pathologists to accumulate experience in NCMH diagnosis to avoid misdiagnosis.

Nasal chondromesenchymal hamartoma (NCMH): a rare DICER1-associated tumour in an adult male

An adult male presented to the ENT clinic with a 1-year history of unilateral nasal blockage. He had presented to another institution 5 years previously with the same issue, undergoing resection of what was reported to be a benign inflammatory polyp with osseous metaplasia. Detailed examination revealed a large mass filling the left nasal cavity. Excisional biopsy and secondary specialist review of pathology revealed nasal chondromesenchymal hamartoma (NCMH) with associated DICER1 mutations. NCMH is a rare, benign tumour of the sinonasal tract, presenting more often in the early childhood, with symptoms related to the site and extent of the tumour. As highlighted in this case, complete excision is mandatory for definitive diagnosis and treatment of NCMH, and an awareness of the association with DICER1 mutation, which can predispose individuals to a range of neoplasia, is key to providing appropriate genetic counselling.

Chondromesenchymal Hamartoma With Nasopharyngeal Involvement: Two Unusual Cases of an Extremely Rare Lesion

Chondromesenchymal hamartoma (CMH) is a rare, benign lesion of the nasal cavity, paranasal sinuses, and skull base, composed of islands of hyaline cartilage in a myxoid background. The vast majority of CMH cases are infants and young children. According to the world literature, nasopharyngeal involvement of CMH is extremely rare. In all cases, the lesions were masses protruding from the nasal cavity or paranasal sinuses to the nasopharynx. We hereby report 2 adult male patients with masses completely situated in the nasopharyngeal space. In the first patient, the tumor originated from the posterior edge of the nasal septum and in the second one, from the posterolateral wall of the nasopharynx, adjacent to the pharyngeal orifice of the Eustachian tube. In both patients, the lesion was excised endoscopically, and histopathological analyses were consistent with a diagnosis of CMH. To our knowledge, those are the only cases of CMH completely situated in the nasopharynx.

A Systematic Review of Nasal Chondromesenchymal Hamartoma (NCMH) with a New Case Report

Nasal chondromesenchymal hamartoma (NCMH) is a very rare, benign sinonasal tract tumor commonly affecting infants. In this paper, in addition to presenting a systematic review of the literature on NCMH, we also report an unusual case of NCMH in an adolescent patient. A systematic review conducted following the PRISMA guidelines. PubMed, EMBASE and manual search through references of relevant publication were utilised to gather all published case-reports of NCMH. Data collected from each case-report for patient demographics, site and size of NCMH, clinical presentation, co-morbidities, diagnostic methods, treatment options and follow-up methods. The systemic review collected sixty-two case-reports of NCMH (including our case) affecting 42 men and 21 women (2:1 male to female ratio). Mean average age was 5.1 years (age range: 1 day to 70 years). The anatomical sites of the tumor were: nasal cavity (n = 17), paranasal sinuses (n = 30), orbital region (n = 17), and the base of the skull (n = 16). The reported clinical manifestations were nasal obstruction or congestion (n = 29), nasal mass (n = 27), epistaxis (n = 6), orbital symptoms (n = 14). NCMH is a very rare cause of nasal masses in infants and toddlers. Our case and previous case reports confirm that NCMH can mimic other benign and malignant tumors, therefore we should be vigilant for rare pathologies that lead to nasal masses. Recently the link between DIECR1 mutation with NCMH has been established, so NCMH should be considered in any patient with nasal or orbital symptoms with a history of DICER1-related tumor spectrum.

PRAME protein expression in DICER1-related tumours

DICER1 syndrome is an autosomal dominant tumour predisposition syndrome usually affecting persons under 30 years of age. Many of the associated benign and malignant lesions occur almost exclusively in DICER1 syndrome. One such tumour, pituitary blastoma (pitB), overexpresses PRAME 500x above control levels. PRAME (PReferentially expressed Antigen in MElanoma) is expressed in malignancies that are not DICER1-related (e.g. melanoma). To address whether PRAME expression is part of the DICER1 phenotype, or simply a feature of pitB, a series of 75 DICER1-mutated specimens and 33 non-mutated specimens was surveyed using immunohistochemistry for PRAME, together with EZH2, which complexes with PRAME. In DICER1-mutated specimens, positive staining for PRAME was only seen in malignant tumours; 7 of 11 histological types and 34/62 individual tumours were positive, while non-tumourous lesions were always negative. Pleuropulmonary blastoma (PPB) showed a continuum in staining, with type I lesions being PRAME negative (n = 7) but all type II and type III lesions PRAME positive (n = 7). Similarly, cystic nephroma (CN) was negative (n = 8), with anaplastic sarcoma of the kidney being positive (n = 2). However, one atypical CN with mesenchymal cell proliferation was PRAME-positive. Embryonal rhabdomyosarcoma (RMS) with DICER1 pathogenic variants (PVs) was positive for PRAME (5/6), but the same tumour type without DICER1 PVs was also positive (9/15). Staining for EZH2 corresponded to that seen with PRAME, validating the latter. This study leads us to conclude that (1) PRAME expression occurs in two-thirds of DICER1-related malignancies; (2) PRAME may be a marker for the progression that certain DICER1-related lesions are thought to undergo, such as PPB and CN; and (3) PRAME expression in some tumours, such as RMS, appears to be an intrinsic feature of the tumour, rather than specifically related to DICER1 PVs. Therapy directed against PRAME may offer novel treatment options in patients with the DICER1 syndrome.

Update from the 5th Edition of the World Health Organization Classification of Head and Neck Tumors: Nasal Cavity, Paranasal Sinuses and Skull Base

The World Health Organization Classification of Head and Neck Tumours recently published the 5th edition. There are new entities, emerging entities, and significant updates to the taxonomy and characterization of tumor and tumor-like lesions, specifically in this article as it relates to nasal cavity, paranasal sinuses and skull base. Importantly, the number of diagnostic entries has been reduced by creating category-specific chapters for soft tissue, hematolymphoid, melanocytic, neuroectodermal, and metastatic tumors. Bone and salivary gland tumors are also not separately reported in the sinonasal tract, but included in the jaw and salivary gland sections, respectively. Repetition of characteristic entities in each anatomic site was also reduced, instead highlighting only the unique features in each anatomic site. Two new entities (SWI/SNF complex-deficient sinonasal carcinomas and HPV-related multiphenotypic sinonasal carcinoma) will be highlighted in this review, with a discussion of several emerging entities. There is a short description of updated information for all 24 diagnostic entities included in this edition to allow the reader a snapshot of current state of knowledge, but to encourage more investigation and further broaden understanding of these diverse and rare entities.

Sinonasal Hamartomas: From Nasal Chondromesenchymal Hamartoma to Respiratory Epithelial Adenomatoid Hamartoma. Report of six Cases and Review of the Literature

Sinonasal hamartomas are uncommon lesions of nasal and sinus cavities. Based on indigenous cellular components and characteristic histologic features, they are further classified into four entities: respiratory epithelial adenomatoid hamartoma (REAH), seromucinous hamartoma (SH), chondro-osseous and respiratory epithelial hamartoma (CORE), and nasal chondromesenchymal hamartoma (NCH). REAH, SH, and CORE are seen in adult patients, while NCH predominantly occurs in newborns and infants. Morphologically REAH and SH are composed of respiratory epithelium and seromucinous glands, CORE is related to REAH but with additional feature of chondroid and/or osseous tissue, and NCH is composed of chondroid and stromal elements but devoid of epithelial component. All four lesions can present as sinonasal mass lesions and with associated obstructive symptoms. Given the rarity of these lesions, diagnosis can be challenging, especially in unusual clinical scenario. In this study, we report six cases of sinonasal hamartoma, including one case of NCH, one case of CORE, two cases of SH, and two cases of REAH. All cases were from adult patients including four men and two women. We also review the literature of the clinical and pathologic features of these rare lesions.

DICER1 tumor predisposition syndrome: an evolving story initiated with the pleuropulmonary blastoma

DICER1 syndrome (OMIM 606241, 601200) is a rare autosomal dominant familial tumor predisposition disorder with a heterozygous DICER1 germline mutation. The most common tumor seen clinically is the pleuropulmonary blastoma (PPB), a lung neoplasm of early childhood which is classified on its morphologic features into four types (IR, I, II and III) with tumor progression over time within the first 4-5 years of life from the prognostically favorable cystic type I to the unfavorable solid type III. Following the initial report of PPB, its association with other cystic neoplasms was demonstrated in family studies. The detection of the germline mutation in DICER1 provided the opportunity to identify and continue to recognize a number seemingly unrelated extrapulmonary neoplasms: Sertoli-Leydig cell tumor, gynandroblastoma, embryonal rhabdomyosarcomas of the cervix and other sites, multinodular goiter, differentiated and poorly differentiated thyroid carcinoma, cervical-thyroid teratoma, cystic nephroma-anaplastic sarcoma of kidney, nasal chondromesenchymal hamartoma, intestinal juvenile-like hamartomatous polyp, ciliary body medulloepithelioma, pituitary blastoma, pineoblastoma, primary central nervous system sarcoma, embryonal tumor with multilayered rosettes-like cerebellar tumor, PPB-like peritoneal sarcoma, DICER1-associated presacral malignant teratoid neoplasm and other non-neoplastic associations. Each of these neoplasms is characterized by a second somatic mutation in DICER1. In this review, we have summarized the salient clinicopathologic aspects of these tumors whose histopathologic features have several overlapping morphologic attributes particularly the primitive mesenchyme often with rhabdomyoblastic and chondroid differentiation and an uncommitted spindle cell pattern. Several of these tumors have an initial cystic stage from which there is progression to a high grade, complex patterned neoplasm. These pathologic findings in the appropriate clinical setting should serve to alert the pathologist to the possibility of a DICER1-associated neoplasm and initiate appropriate testing on the neoplasm and to alert the clinician about the concern for a DICER1 mutation.

Clinicians Practicing Obstetrics and Gynecology Are Uniquely Situated to Recognize DICER1 Syndrome

Pediatric gynecologic malignancies are rare, present with diverse pathologic findings, and can be associated with genetic syndromes such as Peutz-Jeghers, Lynch, and Li-Fraumeni. DICER1 mutation is an emerging entity that has been demonstrated to cause a hereditary tumor predisposition syndrome. Previously, gynecologic manifestations of DICER1 syndrome have been described in single or small case reports with an array of pathologic findings. Here, we discuss pediatric and adolescent patients with gynecologic DICER1-associated tumors, outline the significance of DICER1, and suggest points of care where the syndrome may be diagnosed in the context of routine obstetric and gynecology practice. Patients presenting with a personal or family history suspicious for DICER1 syndrome should undergo both germline and somatic testing, as the presence of DICER1 mutations will have an impact on both treatment and surveillance strategies.

DICER1 Syndrome and Cancer Predisposition: From a Rare Pediatric Tumor to Lifetime Risk

DICER1 syndrome is a rare genetic condition predisposing to hereditary cancer and caused by variants in the DICER1 gene. The risk to present a neoplasm before the age of 10 years is 5.3 and 31.5% before the age of 60. DICER1 variants have been associated with a syndrome involving familial pleuropulmonary blastoma (PPB), a rare malignant tumor of the lung, which occurs primarily in children under the age of 6 years and represents the most common life-threatening manifestation of DICER1 syndrome. Type I, II, III, and Ir (type I regressed) PPB are reported with a 5-year overall survival ranging from 53 to 100% (for type Ir). DICER1 gene should be screened in all patients with PPB and considered in other tumors mainly in thyroid neoplasms (multinodular goiter, thyroid cancer, adenomas), ovarian tumors (Sertoli-Leydig cell tumor, sarcoma, and gynandroblastoma), and cystic nephroma. A prompt identification of this syndrome is necessary to plan a correct follow-up and screening during lifetime.

Pediatric Nasal Chondromesenchymal Tumors: Case Report and Review of the Literature

INTRODUCTION

Nasal chondromesenchymal tumors (NCMT) are rare benign neoplasms that usually present in children <1 year of age. They can display rapid growth and significant local bony remodeling that can mimic a malignant process. Of the ∼50 published cases to date, few have documented the need for neurosurgical intervention. We herein report a NCMT in an infant treated with a staged cranial and transnasal approach, as well as summarize the available literature on this pathology.

CASE REPORT

A newborn male with a compromised airway was noted to have a large sinonasal lesion. After stabilization, MRI demonstrated a 4-cm enhancing mass with diffuse sinus involvement and significant extension into the anterior cranial fossa, with displacement of the optic apparatus and hypothalamic pituitary axis. After an initial biopsy, the patient underwent a bifrontal craniofacial approach at 2 months of age, followed by a second-stage transnasal endoscopic approach at 15 months which resulted in a complete resection. There were no neurosurgical complications. Pathology was consistent with a NCMT.

DISCUSSION

Although rare, neurosurgical involvement is critical for the treatment of NCMTs with intracranial extension. Staged cranial and endonasal endoscopic approaches may be needed for complete resection of such lesions.

Nasal Chondromesenchymal Hamartoma

Nasal chondromesenchymal hamartoma (NCMH) is a rare, benign lesion of the sinonasal tract. It usually presents as a polypoid mass in infants and older children. Imaging studies and endoscopy are required to delineate the extent of the lesion and aid in its excision. This unusual lesion is composed of proliferating mesenchymal and cartilaginous elements. Recently, a genetic association between NCMH and DICER1 mutation has been established. It is important for pathologists to be familiar with this entity to avoid misdiagnosis since the lesion is benign and surgical excision is curative.

Imaging of DICER1 syndrome

DICER1 syndrome is a highly pleiotropic tumor predisposition syndrome that has been increasingly recognized in the last 10 years. Diseases in the syndrome result from mutations in both copies of the gene DICER1, a highly conserved gene that is critically implicated in micro-ribonucleic acid (miRNA) biogenesis and hence modulation of messenger RNAs. In general, susceptible individuals carry an inherited germline mutation that disables one copy of DICER1; within tumors, a very characteristic second mutation alters function of the other gene copy. About 20 hamartomatous, hyperplastic or neoplastic conditions comprise DICER1 syndrome. Most are not life-threatening, but some are aggressive malignancies. There are many unaffected carriers because penetrance is generally low; however, clinically occult thyroid nodules and lung cysts are frequent. Rare diseases of early childhood were the first recognized conditions in DICER1 syndrome, while other conditions affect adolescents and adults. The hallmarks of DICER1 syndrome are certain rare tumors including pleuropulmonary blastoma; cystic nephroma; ovarian Sertoli-Leydig cell tumor; sarcomas of the cervix, kidneys and cerebrum; pituitary blastoma; ciliary body medulloepithelioma; and nasal chondromesenchymal hamartoma. Radiologists are often the first practitioners to observe these diverse manifestations and play a primary role in recognizing DICER1 syndrome.

Nasal Chondromesenchymal Hamartoma: Rare Case Report in an Elderly Patient and Brief Review of Literature

Hamartomas are considered a mixture of nonneoplastic tissue, which may be indigenous to a different location in the body. As such, they may be epithelial, mesenchymal, or mixed. In the sinonasal region, the following hamartomatous lesions are considered to lie on a spectrum and include respiratory epithelial adenomatoid hamartoma (REAH), chondro-osseous respiratory epithelial adenomatoid hamartoma (COREAH), and nasal chondromesenchymal hamartoma (NCMH). To our knowledge, less than 50 cases of sinonasal hamartomas have been reported in the English literature so far with NCMH being very rare and primarily a tumor in infancy, with only 2 cases reported in individuals older than 16 years of age. We report a highly unusual case of a NCMH in the right maxillary sinus of a 70-year-old female.

Strong Expression and Amplification of IGF1R in Pleuropulmonary Blastomas

Pleuropulmonary blastoma (PPB) is a rare malignant intrathoracic tumor primarily affecting children under 5 years of age. PPBs are histologically divided into 3 subtypes: Type 1 PPBs are composed of multiple cysts, and type 3 is a solid lesion with a variable morphologic appearance. Type 2 has a mixed morphology consisting of cystic and solid areas. The genetics of PPB are poorly understood. We analyzed 16 cases of the Kiel Paediatric Tumor Registry with the diagnosis of PPB by comparative genomic hybridization and confirmed some genetic changes by fluorescence in situ hybridization. Furthermore, we performed immunohistochemistry to evaluate insulin-like growth factor type 1 (IGF1R) protein expression. Frequent findings by comparative genomic hybridization were losses on 4q, 5q, 9p and gains on chromosome 8, 17, and 20q. Genomic amplification was observed in 5 cases, 4 related to 15q25qter and 1 to 1p. Fluorescence in situ hybridization could confirm 7 gains of chromosome 8 (7/16, 44%) and 4 amplifications of the IGF1R-gene on 15q26 (4/16, 25%). All of the tumors with IGF1R amplification were type 3 PPBs. One of the PPBs with gain of chromosome 8 was a type 2 tumor and 6 tumors were type 3 PPBs. All but one PPB showed an IGF1R expression by immunohistochemistry. In our series of 16 PPBs, 25% of the tumors have an amplification of the IGF1R gene and 44% show a gain of chromosome 8. All of the tumors with IGF1R amplification were PPBs type 3, indicating that it is a later event in tumor progression, while the gain of chromosome 8 was found in both type 2 and type 3 tumors indicating that these changes are probably earlier events in tumor development. Furthermore, the strong IGF1R protein expression could be a possible therapeutic target in refractory chemoresistant PPBs.

Endoscopic endonasal excision of nasal chondromesenchymal hamartoma with intracranial extension

INTRODUCTION

Nasal chondromesenchymal hamartoma (NCMH) is an extremely rare benign hamartoma of the sinonasal tract, predominantly involving infants and young children.

METHODS

We report the case of a 3-year-old boy of NCMH with extension to anterior skull base.

RESULTS

The tumor was completely resected piece by piece via an endonasal endoscopic approach. There is no recurrence 3 years after operation.

CONCLUSIONS

We reported the case of NCMH extending to skull base was successfully resected by endonasal endoscopic approach.

Selected Diagnostically Challenging Pediatric Soft Tissue Tumors

Many benign and malignant soft tissue tumors in children are challenging and their diagnosis requires knowledge of their vast diversity, histopathological complexity, and immunohistochemical, cytogenetic, and molecular characteristics. The importance of clinical and imaging features cannot be overstated. Soft tissue sarcomas account for 15% of all pediatric malignancies after leukemia/lymphoma, central nervous system tumors, neuroblastoma and Wilms tumor. This article discusses selected challenging pediatric soft tissue tumors with an update on recently described entities.

Hodgkin lymphoma as a novel presentation of familial DICER1 syndrome

DICER1 germline mutations are associated with an inherited cancer syndrome, most commonly presenting with pleuropulmonary blastoma (PPB), ovarian sex cord tumors, thyroid cysts/goitre, and cystic nephroma. We describe the occurrence of a Hodgkin lymphoma (HL) of the T cell phenotype in a family with DICER1 syndrome. The patient presented with PPB Type I and HL. Immunohistochemical staining of the Hodgkin and Reed-Sternberg cells revealed CD30, TGP, CD2, CD3, CD15, and IRF4 positivity and weekly positivity of PAX5. T cell receptor repertoire analysis suggested HL of T cell origin, which is in contrast to common B cell-derived HL. The mother had been diagnosed with thyroid cysts, one sister had died from a primitive neuroectodermal tumor, and a brother had died from PPB Type III. Two mutational events were revealed in all affected family members; a single bp deletion, c.5299delC, leading to a frameshift and premature stop in exon 24 and a heterozygous variant (c.4616C>T; p.Thr1539Met) located in exon 23 of the DICER1 gene. This variant is predicted to be benign by in silico analysis.

CONCLUSION

Future studies looking for DICER1 mutations in HL cases of the T cell phenotype will be important to confirm its association with constitutional DICER1 syndrome.

WHAT IS KNOWN

• DICER1 germline mutations are associated with an inherited cancer syndrome, most commonly pleuropulmonary blastoma, ovarian sex cord tumors, thyroid cysts/goitre, and cystic nephroma. • Hodgkin lymphoma is one of the most frequent types of malignant lymphomas and typically arises sporadically. T cell-derived Hodgkin lymphomas are exceptionally rare. What is New: • DICER1 syndrome may have an even broader phenotypic spectrum and seems to be associated with rare forms of T cell Hodgkin lymphoma.

Nasal Chondromesenchymal Hamartoma (NCMH): a systematic review of the literature with a new case report

BACKGROUND

Nasal chondromesenchymal hamartoma (NCMH) is a very rare, benign tumour of the sinonasal tract usually presenting in infants. We present a systematic review of NCMH cases alongside a case report of an adult with asymptomatic NCMH.

METHODS

A systematic review was conducted in accordance with PRISMA guidelines. A PubMed, EMBASE and manual search through references of relevant publications was used to identify all published case-reports of NCMH. Data was collected from each case-report on: patient demographics, laterality, size and location of NCMH, presentation, co-morbidities, investigations, treatment and follow-up.

RESULTS

The systematic review identified 48 patients (including ours): 33 male, 15 female. Mean age was 9.6 years (range: 1 day-69 years) with the majority aged 1 year or younger at presentation (n = 18). Presentations included: nasal congestion (n = 17), nasal mass (n = 15) and eye signs (n = 12). NCMH also involved the paranasal sinuses (n = 26), orbit (n = 16) and skull-base (n = 14). All patients underwent operative resection of NCMH. A small 2014 case-series found DICER1 mutations in 6 NCMH patients, establishing a link to the DICER1 tumour spectrum.

CONCLUSIONS

NCMH is a rare cause of nasal masses in young children and adults. In light of the newly established link between NCMH and DICER1 mutations surgeons should be vigilant for associated DICER1 tumours, as NCMH may be the 'herald tumour' of this disease spectrum.

Diagnosis and treatment of pleuropulmonary blastoma-single center experience

Pleuropulmonary blastoma (PPB) is a rare and potentially aggressive intrathoracic disembryonic neoplasm typically occurring in children less than 6 years of age. We assessed the relative incidence, clinical characteristics, treatment outcome, and the prognostic factors for long-term survival in patients with PPB treated at our institution over a 25-year period, and compared these data with reports in the literature. From 1985 to 2010, 11 children (4 males and 7 females), with a median age of 5.4 years (range, 1-12 years) were treated at our hospital. Here we described the main characteristics of these patients, the diagnostic methods, and treatment modalities used. During a median follow-up period of 80, 9 months, the overall survival (OS) and disease-free survival (DFS) rates were 54, 6% and 45, 5%, respectively. Two patients survived for more than 20 years. The main prognostic factors for long-term survival were the diseases type I and II and treatment with radical surgery. Our results show that in order to improve the prognosis of patients with PPB a timely in our opinion and accurate diagnosis needs to be established and treatment should be offered according to the disease type and extend of dissemination.

Pleuropulmonary blastoma: a report on 350 central pathology-confirmed pleuropulmonary blastoma cases by the International Pleuropulmonary Blastoma Registry

BACKGROUND

Pleuropulmonary blastoma (PPB) has 3 subtypes on a tumor progression pathway ranging from type I (cystic) to type II (cystic/solid) and type III (completely solid). A germline mutation in DICER1 is the genetic cause in the majority of PPB cases.

METHODS

Patients confirmed to have PPB by central pathology review were included, and their clinical characteristics and outcomes were reported. Germline DICER1 mutations were sought with Sanger sequencing.

RESULTS

There were 435 cases, and a central review confirmed 350 cases to be PPB; 85 cases (20%) were another entity. Thirty-three percent of the 350 PPB cases were type I or type I regressed (type Ir), 35% were type II, and 32% were type III or type II/III. The median ages at diagnosis for type I, type II, and type III patients were 8, 35, and 41 months, respectively. The 5-year overall survival (OS) rate for type I/Ir patients was 91%; all deaths in this group were due to progression to type II or III. OS was significantly better for type II versus type III (P = .0061); the 5-year OS rates were 71% and 53%, respectively. Disease-free survival (DFS) was also significantly better for type II versus type III (P = .0002); the 5-year DFS rates were 59% and 37%, respectively. The PPB type was the strongest predictor of outcome. Metastatic disease at the diagnosis of types II and III was also an independent unfavorable prognostic factor. Sixty-six percent of the 97 patients tested had a heterozygous germline DICER1 mutation. In this subset, the DICER1 germline mutation status was not related to the outcome.

CONCLUSIONS

Cystic type I/Ir PPB has a better prognosis than type II, and type II has a better outcome than type III. Surveillance of DICER1 carriers may allow the earlier detection of cystic PPB before its progression to type II or III PPB and thereby improve outcomes.

Germ-line and somatic DICER1 mutations in pineoblastoma

Germ-line RB-1 mutations predispose to pineoblastoma (PinB), but other predisposing genetic factors are not well established. We recently identified a germ-line DICER1 mutation in a child with a PinB. This was accompanied by loss of heterozygosity (LOH) of the wild-type allele within the tumour. We set out to establish the prevalence of DICER1 mutations in an opportunistically ascertained series of PinBs. Twenty-one PinB cases were studied: Eighteen cases had not undergone previous testing for DICER1 mutations; three patients were known carriers of germ-line DICER1 mutations. The eighteen PinBs were sequenced by Sanger and/or Fluidigm-based next-generation sequencing to identify DICER1 mutations in blood gDNA and/or tumour gDNA. Testing for somatic DICER1 mutations was also conducted on one case with a known germ-line DICER1 mutation. From the eighteen PinBs, we identified four deleterious DICER1 mutations, three of which were germ line in origin, and one for which a germ line versus somatic origin could not be determined; in all four, the second allele was also inactivated leading to complete loss of DICER1 protein. No somatic DICER1 RNase IIIb mutations were identified. One PinB arising in a germ-line DICER1 mutation carrier was found to have LOH. This study suggests that germ-line DICER1 mutations make a clinically significant contribution to PinB, establishing DICER1 as an important susceptibility gene for PinB and demonstrates PinB to be a manifestation of a germ-line DICER1 mutation. The means by which the second allele is inactivated may differ from other DICER1-related tumours.

DICER1: mutations, microRNAs and mechanisms

Dicer is central to microRNA-mediated silencing and several other RNA interference phenomena that are profoundly embedded in cancer gene networks. Most recently, both germline and somatic mutations in DICER1 have been identified in diverse types of cancer. Although some of the mutations clearly reduce the dosage of this key enzyme, others dictate surprisingly specific changes in select classes of small RNAs. This Review reflects on the molecular properties of the Dicer enzymes in small RNA silencing pathways, and rationalizes the newly discovered mutations on the basis of the activities and functions of its determinants.

Nasal chondromesenchymal hamartomas arise secondary to germline and somatic mutations of DICER1 in the pleuropulmonary blastoma tumor predisposition disorder

Nasal chondromesenchymal hamartoma (NCMH) is a rare nasal tumor that typically presents in young children. We previously reported on NCMH occurrence in children with pleuropulmonary blastoma (PPB), a rare pulmonary dysembryonic sarcoma that is the hallmark neoplasm in the PPB-associated DICER1 tumor predisposition disorder. Original pathologic materials from individuals with a PPB, PPB-associated tumor and/or a DICER1 mutation were centrally reviewed by the International PPB Registry. Paraffin-embedded NCMH tumor tissue was available in three cases. Laser-capture microdissection was used to isolate mesenchymal spindle cells and cartilage in one case for Sanger sequencing of DICER1. Nine patients (5F/4M) had PPB and NCMH. NCMH was diagnosed at a median age of 10 years (range 6-21 years). NCMH developed 4.5-13 years after PPB. Presenting NCMH symptoms included chronic sinusitis and nasal congestion. Five patients had bilateral tumors. Local NCMH recurrences required several surgical resections in two patients, but all nine patients were alive at 0-16 years of follow-up. Pathogenic germline DICER1 mutations were found in 6/8 NCMH patients tested. In 2 of the patients with germline DICER1 mutations, somatic DICER1 missense mutations were also identified in their NCMH (E1813D; n = 2). Three additional PPB patients developed other nasal lesions seen in the general population (a Schneiderian papilloma, chronic sinusitis with cysts, and allergic nasal polyps with eosinophils). Two of these patients had germline DICER1 mutations. Pathogenic germline and somatic mutations of DICER1 in NCMH establishes that the genetic etiology of NCMH is similar to PPB, despite the disparate biological potential of these neoplasms.

DICER1-pleuropulmonary blastoma familial tumor predisposition syndrome: a unique constellation of neoplastic conditions

Germline mutations in DICER1 are associated with increased risk for a wide variety of neoplastic conditions, including pleuropulmonary blastoma (PPB), cystic nephroma, nasal chondromesenchymal hamartoma, ovarian Sertoli-Leydig cell tumors, botryoid embryonal rhabdomyosarcoma of the uterine cervix, ciliary body medulloepithelioma, pineoblastoma, pituitary blastoma and nodular thyroid hyperplasia or thyroid carcinoma. These tumors may be seen in isolation or in constellation with other characteristic tumor types in individuals or family members. Here we describe the medical history of a child with a heterozygous, loss of function germline DICER1 mutation and multiple tumors associated with the syndrome.. Although germline mutations in DICER1 are rare, tumors of these types will be seen by practicing pathologists and should prompt consideration of an underlying DICER1 mutation.

Pleuropulmonary blastoma: a single-institution experience

Pleuropulmonary blastoma (PPB) is a rare primary intrathoracic mesenchymal malignancy that occurs exclusively in early childhood. Twelve patients were diagnosed with PPB (1 type I, 5 type II, and 6 type III) between 1979 and 2009 at our institution. Upfront complete tumor resection was successful in 5 of 6 patients. Six patients had biopsy followed by neoadjuvant chemotherapy, 2 had complete tumor resection, and 2 had microscopic residual disease after surgery. All patients received vincristine, dactinomycin, and cyclophosphamide chemotherapy. Eight received additional chemotherapy with doxorubicin, cisplatin, etoposide, or ifosfamide. Three patients received local irradiation. The 5-year event-free and overall survivals were 33% ± 14% and 42% ± 14%, respectively. Median time to progression was 8 months. Five of 9 patients with gross total resection survived, whereas all 3 with gross residual disease died. Three of 5 survivors did not receive radiation. A high index of suspicion for PPB must be maintained in all patients diagnosed with intrathoracic sarcoma in early childhood. Gross total resection is necessary for cure, and selected patients do not require radiation therapy.

Nasal chondromesenchymal hamartoma with no nasal symptoms

The authors present a case of nasal chondromesenchymal hamartoma (NCMH) in an 8-year-old boy with a 4-month history of frontal headache and no symptoms of nasal obstruction, rhinorrhoea or postnasal drip. An ENT examination as well as ophthalmology assessment presented normal results. CT scan showed a lesion involving the sphenoid and ethmoid sinuses. The patient had an endoscopic resection of the lesion that was confirmed histologically to be a NCMH. Though NCMH is known to present usually in infants with obstructing nasal mass, an unusual presentation of a patient with throbbing headache without any nasal symptoms is reported here.

Translocation t(12;17)(q24.1;q21) as the sole anomaly in a nasal chondromesenchymal hamartoma arising in a patient with pleuropulmonary blastoma

The identification of recurrent chromosomal abnormalities in benign and malignant mesenchymal neoplasms has provided important pathogenetic insight as well as powerful diagnostic adjuncts. Nasal chondromesenchymal hamartoma (NCMH), an extremely rare benign tumor arising in the sinonasal tract of infants and children, has not been previously subjected to cytogenetic analysis. Histopathologically composed of mixed mesenchymal elements, NCMH exhibits a relatively wide differential diagnosis to include chondromyxoid fibroma, chondroblastoma, aneurysmal bone cyst, fibrous dysplasia, and osteochondromyxoma. An interesting association with pleuropulmonary blastoma has been reported in a small subset of NCMH patients. In the current study, cytogenetic analysis of a NCMH arising in an 11-year-old boy with a past medical history of pleuropulmonary blastoma revealed a novel 12;17 translocation, t(12;17)(q24.1;q21), as the sole anomaly.

Ovarian sex cord-stromal tumors, pleuropulmonary blastoma and DICER1 mutations: a report from the International Pleuropulmonary Blastoma Registry

OBJECTIVE

Pleuropulmonary blastoma (PPB) is a childhood cancer arising from pleuropulmonary mesenchyme. This neoplasm is a sentinel disease in a familial tumor syndrome recently found to be associated with germline mutations in DICER1. Observations of ovarian sex cord-stromal tumors (OSCST) in PPB kindreds led to further study. We sought to characterize ovarian tumors seen in probands and families with PPB and PPB-related conditions and define germline DICER1 status.

METHODS

Patient and family records of pathology-reviewed PPB cases enrolled in the International PPB Registry (IPPBR) were searched for ovarian tumors. Ovarian tumor pathology specimens were obtained and centrally reviewed. Germline DNA from patients with ovarian tumors was tested for DICER1 mutations. Three additional OSCST patients registered in the IPPBR were also tested for mutations in DICER1.

RESULTS

Among 296 kindreds including 325 children with PPB, we observed three children with both PPB and Sertoli-Leydig cell tumors (SLCT)/Sertoli cell tumors. Among family members of PPB patients, we identified six OSCST (three SLCT, one Sertoli cell tumor, one juvenile granulosa cell tumor, one gynandroblastoma). Age at ovarian tumor diagnosis was youngest in PPB probands and younger in family members than in OSCST in general. Germline DICER1 mutations were identified in four of six patients with OSCST from PPB kindreds and in two of three children with OSCST and no personal or family history of PPB.

CONCLUSIONS

Primary ovarian neoplasms, particularly OSCST, are a manifestation of the familial PPB syndrome and may be the initial clinical presentation of DICER1 mutations within a family.