Beta-catenin expression in pediatric fibroblastic and myofibroblastic lesions: a study of 100 cases

Oral nodular fasciitis – A case report with a diagnostic schema

Introduction: The spectrum of myofibroblastic lesions of the oral cavity ranges from reactive to benign to malignant lesions with overlapping histopathologic and immunohistologic characteristics posing a diagnostic dilemma. Observation: A 30-year-old male presented with a spontaneous swelling over the right lower buccal gingiva giving a clinical suspicion of a benign mesenchymal tumor. The lesion presented with a varied biphasic microscopic appearance that posed as a challenge for diagnosis. Commentaries: The incisional biopsy of the lesion showed a highly collagenous stroma with spindle-shaped cells, while the excision biopsy revealed myxoid and hyalinized stroma. A panel of markers comprising of SMA (smooth muscle actin). CD-34, β-Catenin, and Alcian blue stain was employed to arrive at a diagnosis. Conclusion: Most myofibroblastic lesions present with diverse histological appearance which warrants a thorough assessment of the cellular and stromal components for an accurate diagnosis.

Hamartomas of skin and soft tissue

Hamartomas are benign lesions composed of aberrant disorganized growth of mature tissues. Choristomas are similar, except that they are composed of tissues not normally found at the anatomic site in which the lesion is arising. A wide range of hamartomas and choristomas can arise in the skin and soft tissue. Some of these may cause diagnostic difficulty and potentially be mistaken for neoplasms. Some neoplasms may resemble hamaratomas. Here we review the current clinical and pathologic features of these lesions, both common and rare, and discuss how to distinguish them from other entities in the differential diagnosis.

Nonepithelial Tumors and Tumor-like Lesions of the Skin and Subcutis in Children

This overview of mesenchymal tumors presenting in the skin and/or subcutis in children brings together the range of neoplasms and hamartomas which are seen in this age-group. It is not surprising from the perspective of the pediatric or general surgical pathologist that vascular anomalies, including true neoplasms and vascular malformations, are the common phenotypic category. Since there is considerable morphologic overlap among these lesions, clinicopathologic correlation may be more important than for many of the other mesenchymal tumors. The skin and subcutis are the most common sites of clinical presentation for the infantile myofibroma which is the most common of fibrous mesenchymal tumors in children. Several of the other mesenchymal tumors are more common adults-like dermatofibrosarcoma protuberans, but nonetheless have an important presence in children, even as a congenital neoplasm. A lipomatous tumor in a young child should be considered as a possible manifestation of an overgrowth syndrome.

Fibrous hamartoma of infancy: a clinicopathologic study of 145 cases, including 2 with sarcomatous features

Fibrous hamartoma of infancy is a rare soft tissue lesion of infants and young children with characteristic triphasic morphology, which typically occurs in the axilla and less commonly in other locations. We reviewed 145 cases of fibrous hamartoma of infancy from our consultation archives. Cases occurred in 106 males and 39 females (mean age-15 months; range-birth to 14 years), and involved both typical sites (eg, axilla/back/upper arm) (n=69) and unusual locations (n=76). Six were congenital. The tumors presented as subcutaneous masses and ranged from 0.4 to 17 cm (mean 3 cm). All displayed triphasic morphology, but varied widely in the relative percentages of fat, fibroblastic fascicles, and primitive mesenchyme. Hyalinized zones with cracking artifact, mimicking giant cell fibroblastoma, were present in a 44 (30%) of cases; however FISH for PDGFB gene rearrangement was negative in five tested cases. In addition to classical fibrous hamartoma of infancy, two lesions contained large sarcomatous-appearing foci with high cellularity, high nuclear grade, and brisk mitotic activity. One occurred in a 10-month-old female as a new mass in a congenital fibrous hamartoma of infancy; the other occurred as a leg mass in a 6-year-old male. ETV6 gene rearrangement was negative in the tumor from the 10-month-old female. Genomic microarray (OncoScan) showed normal molecular karyotype in eight tested cases, whereas the two tumors with sarcomatous features showed a hyperdiploid/near tetraploid molecular karyotype with copy neutral loss of heterozygosity of chromosomes 1p and 11p, and loss of 10p, chromosome 14, and a large portion of chromosome 22q (22q11.23q13.33), respectively. Follow-up (52 patients; range: 1-208 months, median: 8 months) showed only two local recurrences and no metastases. Extensive local disease in the 10-month-old female with sarcomatous-appearing fibrous hamartoma of infancy necessitated forequarter amputation. In summary, our study confirms the classic clinicopathologic features, including the triphasic morphologic appearance of most cases. In contrast to earlier studies, our series illustrates a broader histologic spectrum than previously appreciated, including its close resemblance to giant cell fibroblastoma in one quarter of cases and the rare presence of 'sarcomatous' areas, the latter providing evidence that these are complex neoplasms rather than hamartomas.

Fibromatosis of the Sigmoid Colon With CTNNB1 (β-Catenin) Gene Mutation, Arising at the Site of Ileocolic Anastomosis for Resection of Gastrointestinal Stromal Tumor

We describe a case of intra-abdominal fibromatosis, which occurred in a 44-year-old woman who had a previous history of gastrointestinal stromal tumor (GIST) of the sigmoid mesocolon, which was treated with imatinib and resection. A mass was detected at the site of ileocolic anastomosis of the previous small bowel resection and sigmoid colectomy, nearly 3 years later. Clinically, this was suspected to represent recurrent GIST and was excised, but histology and mutational analysis showed desmoid-type fibromatosis with a mutation in codon 41 of exon 3 of the CTNNB1 (β-catenin) gene. The occurrence of fibromatosis at the site of excision of GIST is very rare, but its recognition is important as the treatment of the two neoplasms differs significantly. As imaging cannot reliably distinguish between these 2 entities, histological diagnosis is crucial for correct clinical management.

Desmoid-type fibromatosis

Desmoid-type fibromatosis is a rare, locally infiltrative, mesenchymal neoplasm that is associated with high rates of local recurrence but lacks the potential to metastasise. The disease affects younger individuals, with a peak age of 30 years, and is the most common cause of an anterior abdominal wall mass in young women of childbearing age. It may, however, involve nearly every body part, including the extremities, head and neck, trunk, and abdominal cavity; as such, desmoid-type fibromatosis may present to a range of general and subspecialty radiologists. These rare tumours have a widely variable clinical presentation and unpredictable natural history, hence input from a soft-tissue tumour centre is recommended, although much of the imaging may be performed at the patient's local hospital. The consensus for treatment has changed over the past decade, with most centres moving away from primary radical surgery towards a front-line 'watch-and-wait' policy. Therefore, imaging has an increasingly important role to play in both the diagnosis and follow-up of these patients. This review will discuss the typical imaging characteristics of these lesions and suggest diagnostic and follow-up magnetic resonance imaging protocols, with details of suitable sequences and scanning intervals.

Is wide resection obsolete for desmoid tumors in children and adolescents? Evaluation of histological margins, immunohistochemical markers, and review of literature

Desmoid fibromatosis is a benign fibroblastic neoplasm with high recurrence rates predominantly observed in pediatric and adolescent patients. The use of wide resection margins has been discussed controversially in literature. In addition, data on non-surgical treatment is limited as phase III studies are still missing. Nineteen patients under the age of 18 years were identified. Tumor location, surgical treatment for primary or recurrent tumors, resection margins, medical neo-/adjuvant treatment, time to recurrence as well as immunohistochemical markers (estrogen receptor, ER α and β, progesterone and androgen receptors, somatostatin, Ki-67, c-kit, platelet-derived growth factor receptors, PDGFRs, α and β, β-catenin) were evaluated. The mean age at diagnosis was 6.6 years, with a mean follow-up of 114 months. Recurrences were detected in four out of nineteen patients. Surprisingly, the recurrence rate was not influenced by type of resection used (R0, R1/2). All samples were tested negative for ER α, somatostatin, and progesterone receptor. In contrast, a majority of tumors showed positive results for PDGFR α and β and β-catenin. No correlation between positive immunohistochemical markers and tumor recurrences was detectable. In conclusion, recurrence rates are not depending on resection type and immunohistochemical markers seem to behave differently in children and adolescents in contrast to adult patients.

Aggressive fibromatosis

Aggressive (deep or desmoid-type) fibromatoses are locally infiltrative collagen-forming tumours with potential for recurrence but not metastasis. They exert their clinical effects primarily in relation to location and have variable biological behaviour. In sporadic cases there are somatic mutations in the β-catenin (CTNNB1) gene on 3p21, resulting in immunohistochemically demonstrable overexpression in nuclei. Fibromatosis in patients with familial adenomatous polyposis (FAP) harbours inactivating germline mutations in the desmoid region of the adenomatous polyposis coli (APC) gene on 5q21-q22. The differential diagnosis includes other myofibroblastic lesions, perineurioma, low grade fibromyxoid sarcoma and, in the abdomen, gastrointestinal stromal tumour and liposarcoma with 'low-grade' dedifferentiation. The primary management is surgical, though some desmoids cease to grow and can be watched. Other therapies have a role in stabilising growth or shrinking tumours. Although no single therapy is effective in all cases, available modalities including irradiation, hormonal therapy, chemotherapy, and receptor tyrosine kinase inhibition can be of value in appropriate clinicopathological subgroups.

CTNNB1 genotyping and APC screening in pediatric desmoid tumors: a proposed algorithm

Desmoid fibromatosis is a rare, locally aggressive fibroblastic/myofibroblastic tumor that occasionally involves children. We examined a series of pediatric desmoids for CTNNB1 mutations, seen in sporadic tumors, and APC germline mutations, associated with familial adenomatous polyposis (FAP). Forty-four desmoids in pediatric patients were identified in the pathology files of 2 large referral centers (1995-2009). Clinical charts were reviewed for history of FAP. Germline APC gene mutations were determined on blood samples from patients presenting with FAP. Immunohistochemistry for beta-catenin was performed. CTNNB1 genotyping was done by Sanger sequencing on formalin-fixed paraffin-embedded tissue. CTNNB1 mutations were observed in 29 of 44 (66%) desmoids, with 3 mutations identified: T41A (64%), S45F (29%), and S45P (7%). Germline APC mutations were present in 7 (16%) desmoid patients. Eight (18%) patients had desmoids that were wild type for CTNNB1 and had no known clinical signs or family history suspicious for FAP at the time of testing or with extended follow up (n  =  6). Beta-catenin nuclear labeling was observed in 38 of 41 (92%) tested cases, 34 (89%) of which showed mutations in either CTNNB1 (n  =  29) or APC (n  =  5). Nuclear localization of beta-catenin was seen in the majority of pediatric desmoids and was most often associated with somatic mutations in CTNNB1. However, a significant proportion of pediatric patients harbored germline mutations in APC. Given the implications, genetic counseling is recommended for children diagnosed with desmoid tumors lacking CTNNB1 mutations because this population is enriched for FAP patients.

Role of β-catenin expression in paediatric mesenchymal lesions: a tissue microarray-based immunohistochemical study

Beta-catenin is a major protein in the Wnt signalling pathway. Although it has been studied in various types of carcinoma, little is known about its expression in mesenchymal tumours. In this study 41 specimens of a variety of mesenchymal childhood tumours were compared to 24 samples of the corresponding adult tumours to assess the diagnostic value of nuclear β-catenin expression using tissue microarray-based immunohistochemistry. Similar to adult sarcoma and fibromatosis, β-catenin was not expressed in the majority of childhood sarcomas, and its nuclear translocation was detected in paediatric fibromatosis; non-negligible levels of nuclear staining in other tumour types demonstrate Wnt pathway activation in mesenchymal neoplasms of childhood and adolescence.

Fibroblastic and myofibroblastic tumors in children and adolescents

Fibroblastic and myofibroblastic tumors in children and adolescents are a relatively common group of soft tissue proliferations that range from reactive to hamartomatous to neoplastic, with a full spectrum of benign, intermediate, and malignant neoplasms. These lesions are diagnostically challenging because of morphologic and immunohistochemical overlap, despite significant clinical, genetic, and prognostic differences. The fibromatoses are a major subgroup, and all types of fibromatoses can occur in the 1st 2 decades of life. Intermediate and malignant fibroblastic-myofibroblastic tumors are an important group that includes variants of fibrosarcoma and other tumors with recurrent cytogenetic or molecular genetic abnormalities and low metastatic potential. Pathologic examination is enhanced by adjunct techniques, such as immunohistochemistry, cytogenetics, and molecular genetics, although morphology provides the ultimate criteria for a specific diagnosis. This article reviews the clinicopathologic features of fibroblastic and myofibroblastic tumors with an emphasis on the unique aspects of these neoplasms in children and adolescents, the use of diagnostic adjuncts, and differential diagnoses.

Analysis of β-catenin expression and exon 3 mutations in pediatric sporadic aggressive fibromatosis

Aggressive fibromatosis is a benign tumor with a high recurrence rate after surgical resection, particularly in children. Abnormal regulation of β-catenin in the presence or absence of a change of genotype has been identified in adult sporadic aggressive fibromatosis. However, the status of β-catenin expression and mutation remains unclear in pediatric patients. The present study was designed to analyze the expression and mutation status of β-catenin in pediatric aggressive fibromatosis. B-catenin expression was analyzed by immunohistochemistry in 32 samples from pediatric patients with aggressive fibromatosis (21 recurrent cases and 11 primary-onset cases) and 15 control subjects. Somatic point mutations in β-catenin exon 3 were identified by sequencing of polymerase chain reaction products. Nuclear expression of β-catenin was detected in 94% (30/32) of aggressive fibromatosis samples and 13% (2/15) of control samples (P < 0.001). Mutations in exon 3 of the β-catenin gene were identified in 78% (25/32) of aggressive fibromatosis samples (19/21 recurrent cases, 6/11 primary-onset cases; P  =  0.032). The primary mutation in the recurrent cases occurred at codon 45 (S45F), while codon 41 (T41A) was most frequently mutated in the primary-onset cases (P  =  0.002). Abnormal expression of β-catenin appears to occur frequently in pediatric aggressive fibromatosis. Muftations in exon 3 of the β-catenin gene, particularly the S45F mutation, may represent risk factors for recurrence in pediatric patients and could potentially be used as prognostic factors.

Identification of Familial Adenomatous Polyposis carriers among children with desmoid tumours

OBJECTIVE

Desmoid tumours are rare mesenchymal tumours with unpredictable progression and high recurrence risk. They can occur sporadically or in association with Familial Adenomatous Polyposis (FAP), which is caused by germline APC mutations. The Wnt/β-catenin pathway has a central role in the pathogenesis of desmoid tumours. These tumours can occur due to either a somatic CTNNB1 or APC mutation but can also be the first manifestation of FAP. Because germline APC analysis is not routinely performed in children with desmoid tumours, the diagnosis FAP may escape detection. The aim of this study is to form guidelines for the identification of possible APC germline mutation carriers among children with desmoid tumours, based on CTNNB1 mutation analysis and immunohistochemical analysis (IHC) for β-catenin.

PATIENTS AND METHODS

We performed IHC of β-catenin and mutation analysis of CTNNB1 and APC in 18 paediatric desmoid tumours, diagnosed between 1990 and 2009 in the Erasmus MC, Rotterdam.

RESULTS

In 11 tumours, IHC showed an abnormal nuclear β-catenin accumulation. In this group a CTNNB1 mutation was detected in seven tumours. In two tumours with an abnormal nuclear β-catenin accumulation and no CTNNB1 mutation, an APC mutation was identified, which appeared to be a germline mutation.

CONCLUSIONS

Aberrant staining of β-catenin in paediatric desmoids helps to identify children at risk for FAP. We recommend to screen paediatric desmoid tumours for nuclear localisation of β-catenin and consequently for CTNNB1 mutations. For patients with nuclear β-catenin expression and no CTNNB1 mutations, APC mutation analysis should be offered after genetic counselling.

Pediatric fibroblastic and myofibroblastic lesions

Fibrous lesions of infancy and childhood are a heterogeneous group of entities composed predominantly of fibroblasts and myofibroblasts, ranging from reactive lesions to neoplasms with a range of malignant potential. Although rare, their correct recognition by histopathology is important clinically as they exhibit a wide range of behaviors and may be associated with distinct underlying syndromes. Contributions from molecular diagnostics have enabled more accurate diagnosis, and have changed our concepts of some tumor types. In this review, we discuss the clinicopathologic spectrum of fibroblastic and myofibroblastic lesions of childhood and adolescence.

Primitive myxoid mesenchymal tumor of infancy: a report of a further case with locally aggressive behavior

We report a case of an 8-month-old child with a primitive myxoid mesenchymal tumor of infancy arising in the thenar eminence. The lesion recurred after conservative excision and was ultimately nonresponsive to chemotherapy, necessitating partial amputation. The patient remains free of disease 5 years after this radical surgery. This is the 1st report of such a tumor since it was initially described by Alaggio and colleagues in 2006. The pathologic differential diagnosis is discussed.

Orbital lipofibromatosis in a child: a case report

PURPOSE

Lipofibromatosis is a rare, benign, soft tissue tumor that typically involves extremities particularly in children. We report a young girl with lipofibromatosis involving the superotemporal quadrant of the left orbit.

CASE REPORT

An 8-year-old girl presented with a history of a gradually expanding mass in the superotemporal quadrant of the left orbit over several years. Orbital imaging showed a soft tissue mass superolateral to the globe with possible infiltration into the lacrimal gland and lateral rectus muscle. The lesion was excised preserving adjacent structures. Histopathological examination revealed that the lesion consisted of adipose tissue with fibroblastic elements, being consistent with a diagnosis of lipofibromatosis. No recurrence of the lesion was seen in 18 months follow-up.

COMMENT

Orbital involvement of lipofibromatosis as reported here is indeed a very rare entity. Diagnosis can be confirmed by histopathological analysis. As the lesion has a tendency to infiltrate into surrounding structures, surgical excision without hampering important structures is a treatment of choice.

Sirolimus therapy for fibromatosis and multifocal renal cell carcinoma in a child with tuberous sclerosis complex

A male with tuberous sclerosis complex (TSC) developed a chest wall fibromatosis and bilateral multifocal renal cell carcinoma (RCC). The fibromatosis tumor was initially resected during infancy but recurred 5 years later. At that time, bilateral RCC was also detected, leading to the resection of the more extensively affected right kidney. In an attempt to avoid bilateral nephrectomies, the patient was treated with the mTOR inhibitor sirolimus. Within 6 months of therapy, the fibromatosis and remaining RCC tumors responded substantially with minimal adverse effects.

[Lipofibromatosis in a 6-year-old girl: a case report]

Lipofibromatosis is a typical soft tissue lesion of childhood which is most likely underdiagnosed. The case of a 6-year-old girl with a palmar tumor is presented. The lesion showed a typical fascicular growth patter into the fatty tissue. Differential diagnosis includes fibrous hamartoma of infancy. Lipofibromatosis is a benign disease but recurrences are not unusual.