The spectrum of pediatric tumors in infancy, childhood, and adolescence: a comprehensive review with emphasis on special techniques in diagnosis

Ultrasound-guided core biopsy with on-site cytology-immediate diagnosis in pediatric oncology

BACKGROUND

Accurate and swift tissue diagnosis is extremely important for the timely initiation of treatment in pediatric oncology. In our department, ultrasound-guided core needle biopsy (US-guided CNB) is used for tissue diagnosis. In 2016, we added on-site cytology, allowing for an immediate primary diagnosis. We retrospectively reviewed our performance in terms of safety and accuracy for CNBs and on-site cytology.

METHODS

All pediatric biopsies performed in our hospital between February 2016 and December 2020, were included. Patient clinical, procedural and follow-up data were collected. CNB pathology and cytology results were compared to the final pathologic diagnosis.

RESULTS

We included 71 patients for which 72 biopsies with on-site touch imprint (TI) cytology were performed; the average latency time to biopsy was 1 day. Altogether, we had 61 tumors, (58 malignant, 3 benign) and 11 other lesions. On-site cytology diagnosed 58 malignant tumors, 3 benign tumors and 11 non-tumor tissues. The cytologist correctly differentiated tumor from inflammation in all cases, and diagnosed the precise tumor type in 57 cases, with an accuracy of 94% for final diagnosis. We had no complications related to the procedure or sedation.

CONCLUSION

US-guided CNB with on-site TI cytology for suspected malignancy in the pediatric population is highly available, safe, and accurate, with real-time diagnosis in most cases. This accelerated diagnostic route has a huge impact on patient care.

Up-To-Date Practical Imaging Evaluation of Neonatal Soft-Tissue Tumors: What Radiologists Need to Know

OBJECTIVE

The purposes of this article are to provide an up-to-date overview of neonatal soft-tissue tumors, including information regarding their unique nature, and to present practical imaging techniques and characteristic imaging findings.

CONCLUSION

Neonatal soft-tissue tumors are a unique set of neoplasms that often have characteristic clinical and imaging findings. Imaging evaluation, mainly with ultrasound and MRI, plays an important role in the initial diagnosis, staging, preoperative assessment, and follow-up evaluation. Clear understanding of practical imaging techniques combined with up-to-date knowledge of characteristic imaging findings can help the radiologist provide a timely and accurate diagnosis of these neoplasms and can lead to optimal neonatal patient care.

Image-guided percutaneous core needle biopsy of soft-tissue masses in the pediatric population

BACKGROUND

A paucity of literature describes the use of imaged-guided percutaneous core needle biopsy for the diagnosis and characterization of pediatric soft-tissue masses and lesions.

OBJECTIVE

To retrospectively determine whether image-guided percutaneous core needle biopsy is adequate for diagnosing and characterizing benign and malignant pediatric soft-tissue masses and lesions.

MATERIALS AND METHODS

We identified children (≤18 years old) who underwent US- or CT-guided percutaneous core needle biopsy of a soft-tissue mass or other lesion between January 2012 and March 2014. Using medical records, we documented the following data: age and gender, site of the mass or lesion, size and number of biopsy specimens, whether the biopsy procedure was diagnostic, whether sufficient tissue was obtained for necessary ancillary testing (e.g., cytogenetic evaluation), and whether there was a procedural complication within 1 week.

RESULTS

One hundred eight soft-tissue masses or lesions were biopsied under imaging guidance in 84 children; 39 (46%) were girls. Mean age ± standard deviation (SD) was 12.1 ± 5.1 years (range 6 months to 18 years). Of these procedures, 105/108 (97%) were diagnostic; 82/108 (76%) were US-guided; 87/108 (81%) were performed using a 17-gauge introducer needle/18-gauge biopsy instrument. The mean number ± SD of core needle biopsy specimens obtained was 8.9 ± 5.0. For newly diagnosed malignancies, adequate tissue was obtained for ancillary testing in 28/30 (93%) masses. One minor complication was documented.

CONCLUSION

Image-guided percutaneous core needle biopsy of pediatric soft-tissue masses is safe, has a high diagnostic rate, and provides sufficient tissue for ancillary testing.

The Continuing Value of Ultrastructural Observation in Central Nervous System Neoplasms in Children

Central nervous system (CNS) neoplasms are the second most common childhood malignancy after leukemia and the most common solid organ neoplasm in children. Diagnostic dilemmas with small specimens from CNS neoplasms are often the result of multifactorial etiologies such as frozen or fixation artifact, biopsy size, or lack of knowledge about rare or unfamiliar entities. Since the late 1950s, ultrastructural examination has been used in the diagnosis of CNS neoplasms, though it has largely been replaced by immunohistochemical and molecular cytogenetic studies. Nowadays, pathologic diagnosis of CNS neoplasms is achieved through intraoperative cytology, light microscopy, immunohistochemistry, and molecular cytogenetic results. However, the utility of electron microscopy (EM) in the final diagnosis of CNS neoplasms and investigation of its pathogenetic origin remains critical. Here, we reviewed the distinguishing ultrastructural features of pediatric CNS neoplasms and emphasize the continuing value of EM in the diagnosis of CNS neoplasms.

Spectrum of nonhematological pediatric tumors: A clinicopathologic study of 385 cases

Background:

The aim of this study is to understand the epidemiology of tumors in children in our region due to a paucity of studies on the histologic review of the childhood tumors in general and benign tumors in particular.

Materials and Methods:

The records of all the tumors diagnosed histopathologically in children <14 years of age during a period of 8-year (2005-2012) were reviewed.

Results:

A total of 385 tumors were seen in the age range of 1 month-14 years with 231 (60%) in boys and 154 (40%) in girls. Highest number of cases, 224 (58.18%) were in the age group of 10-14 years. Benign tumors comprised 275 (71.43%) cases while the malignant tumors accounted for 110 (28.57%) cases. In benign tumors, vascular tumors were in majority with 68 cases, while in malignant category bone tumors were most common with 36 cases.

Conclusions:

Although the exact incidence rate cannot be provided by this hospital-based study, the information is useful in showing patterns of childhood tumors. We included both benign and malignant tumors, while most of the studies in the past have focused mainly on malignant tumors in children.

Disseminated neuroendocrine carcinoma in a pediatric patient: a rare case and diagnostic challenge

A previously healthy 16-year-old female presented with 1-month history of fever, cough, extremity pain, left upper quadrant pain, and night sweats. Imaging studies revealed mediastinal lymphadenopathy, lung and liver masses, and bony lesions. Liver and bone marrow biopsies revealed small tumor cells with a high nuclear cytoplasmic ratio, stippled chromatin, and inconspicuous nucleoli surrounded by bands of collagen. Immunohistochemically, the tumor cells were positive for epithelial (epithelial membrane antigen and cytokeratin AE1/AE3) and neuroendocrine markers (chromogranin and synaptophysin), and negative for other antigens tested, including vimentin, desmin, CD99, and WT-1. The morphologic features and immunohistochemical profile was consistent with neuroendocrine carcinoma. Despite several chemotherapeutic regimens, the patient had progressive disease and enrolled in a phase 1 trial. Thorough histopathologic evaluation, including immunohistochemical stains is a crucial component for diagnosing this rare, aggressive tumor in children and adolescents.

Anaplastic large cell lymphoma: another entity in the differential diagnosis of small round blue cell tumors

We saw in consultation a biopsy specimen from a 6-year old girl with anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALCL). The tumor arose in soft tissue of the neck, and diagnostic tissue was obtained by core needle biopsy. Histologically, the neoplasm was cellular without pattern. Immunohistochemical workup with a large panel of antibodies at another institution showed immunoreactivity for NB84 and neuron specific enolase (dim). Antibodies specific for CD3, CD20, and CD45/LCA were negative; CD30 or ALK were not assessed. Electron microscopy showed cytoplasmic structures thought to be neurosecretory granules. The neoplasm was interpreted initially as a neuroblastoma. At the time of our review, we considered the possibility of ALCL. Immunohistochemical analysis for CD30 showed bright, uniform expression and ALK was positive in a nuclear and cytoplasmic pattern, confirming the diagnosis of ALK+ ALCL. The purpose of this review is to discuss ALK+ ALCL and many of the other entities included under the rubric of small round blue cell tumor, with a focus on tumors that occur in children.

Heritable T-cell malignancy models established in a zebrafish phenotypic screen

T cell neoplasias are common in pediatric oncology, and include acute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LBL). These cancers have worse prognoses than their B cell counterparts, and their treatments carry significant morbidity. While many pediatric malignancies have characteristic translocations, most T lymphocyte-derived diseases lack cytogenetic hallmarks. Lacking these informative lesions, insight into their molecular pathogenesis is less complete. Although dysregulation of the NOTCH1 pathway occurs in a substantial fraction of cases, many other genetic lesions of T cell malignancy have not yet been determined. To address this deficiency, we pioneered a phenotype-driven forward-genetic screen in zebrafish (Danio rerio). Using transgenic fish with T lymphocyte-specific expression of enhanced green fluorescent protein (EGFP), we performed chemical mutagenesis, screened animals for GFP⁺ tumors, and identified multiple lines with a heritable predisposition to T cell malignancy. In each line, patterns of infiltration and morphologic appearance resembled human T-ALL and T-LBL. T cell receptor analyses confirmed their clonality. Malignancies were transplantable and contained leukemia-initiating cells (LIC), like their human correlates. In summary, we have identified multiple zebrafish mutants that recapitulate human T cell neoplasia and show heritable transmission. These vertebrate models provide new genetic platforms for the study of these important human cancers.

PAX immunoreactivity identifies alveolar rhabdomyosarcoma

PAX5 is a member of the paired box transcription factors involved in development and its expression has been well characterized among hematopoietic malignancies of B-cell lineage. Its expression has also been reported in a subset of neuroendocrine carcinomas, urothelial tumors, Merkel cell carcinoma, glioblastoma, and neuroblastoma cell lines. As such, we sought to assess it as a diagnostic marker in the evaluation of pediatric small round blue cell tumors. Tumors selected for evaluation included embryonal rhabdomyosarcoma (55 cases), alveolar rhabdomyosarcoma (ARMS) (51 cases), neuroblastoma (22 cases), Wilms tumor (18 cases), Ewing Family of Tumors (11 cases), lymphoblastic lymphoma (8 cases), hepatoblastoma (6 cases), and granulocytic sarcoma (3 cases) as either cores in a tissue microarray or whole mount sections. All cases were immunostained using an antibody directed toward PAX5 and immunoreactivity was scored semiquantitatively according to percentage of nuclear staining. As expected, all B-cell lymphoblastic lymphomas were strongly immunoreactive against PAX5. Additionally, all Wilms tumors showed staining of variable intensity, most intensely in the epithelial component. Of the rhabdomyosarcoma cases, 34 of 51 (67%) ARMS were immunoreactive whereas none of the 55 embryonal rhabdomyosarcoma cases stained. No other tumor type on the array was immunoreactive toward PAX5. Genetic information was available on 7 ARMS, 5 of which had characteristic translocations involving PAX genes, either t(2:13) or t(1;13). Of the translocation-positive cases, all showed nuclear reactivity toward PAX5, and both the translocation-negative cases did not. Possible explanations of PAX5 staining include aberrant expression of the PAX5 transcription factor, PAX5 expression in normal tissue at the time the tumors most closely recapitulates in development or crossreactivity with another member of the PAX family. PAX3 and PAX7 fusion genes characterize the majority of ARMS making crossreactivity with these proteins an attractive theory, and suggest that PAX5 immunoreactivity may be specific for translocation-positive ARMS. Further study in a larger series of rhabdomyosarcomas is warranted to assess the sensitivity and specificity of PAX5 immunoreactivity for the ARMS variant.

Malignant round cell neoplasia in llamas and alpacas

Malignant round cell neoplasia was identified in 12 llamas and 12 alpacas aged 0-23 years. Mean age of affected alpacas (3.1 years) was significantly less than that of affected llamas (8.0 years). Tumor cell morphology varied from large and often pleomorphic (11 tumors) to small and often homogeneous (13 tumors). Neoplastic lesions were multicentric in 12 cases. Other sites were gastric (5 cases), intra-abdominal (perirenal; 4 cases), intrathoracic (2 cases), and cervical (1 case). Immunohistochemistry with antibodies to CD79alpha, BLA36, and CD3 identified B-cell lymphoma (12 cases) and T-cell lymphoma (6 cases). Six tumors did not express any lymphoid marker and were further immunostained for neuron-specific enolase (NSE), synaptophysin, S-100, glial fibrillary acidic protein (GFAP), and chromogranin A. All 6 of these tumors were negative for GFAP and chromogranin A but expressed 1 or more of the neural markers NSE, synaptophysin, and S-100 and were classified as primitive malignant round cell tumors (PMRCT). Tumor types could not be distinguished on the basis of animal age, gross pathologic appearance, tumor morphology, or tumor location. All animals with lymphoma and 5 with PMRCT died or were euthanatized. One alpaca with a focal cervical PMRCT lived for at least 20 months after diagnosis. Results of this study indicate that malignant round cell tumors in llamas and alpacas are a heterogeneous group that cannot be distinguished on the basis of signalment, postmortem findings, or routine light microscopic findings. Immunohistochemistry is a valuable diagnostic procedure when evaluating malignant round cell neoplasia in llamas and alpacas.