Cytogenetic support for early malignant change in a diffuse neurofibroma not associated with neurofibromatosis

Diffuse neurofibroma with hypertrichosis in a toddler

Diffuse neurofibroma is a rare type of neurofibroma uncommonly reported in infancy. It is a slow growing tumor originating in the peripheral nerve sheath. We present the case of a 17-month-old boy with diffuse neurofibroma of the scalp associated with hypertrichosis. His genetic and clinical workup for neurofibromatosis was negative.

Malignant peripheral nerve sheath tumor (MPNST) arising in diffuse-type neurofibroma: clinicopathologic characterization in a series of 9 cases

Diffuse-type neurofibroma, an uncommon variant of neurofibroma, is associated with neurofibromatosis type 1 in ∼60% of cases. Typically presenting in young adults as ill-defined plaque-like dermal/subcutaneous thickening, most cases are located on the trunk or the head and neck region. Malignant transformation is extremely rare. Nine cases of malignant peripheral nerve sheath tumor (MPNST) arising in diffuse-type neurofibroma (identified in consult files) are described, including clinicopathologic features and follow-up. Five patients were male and 4 female, aged 31 to 59 years (median 49 y). All diffuse-type neurofibromas contained Meissner corpuscles, with tumor sizes ranging between 3.6 and 45 cm (median, 7.4 cm). Five patients had a clinical history of neurofibromatosis type 1, and 1 had Klippel-Trénaunay-Weber syndrome. Six tumors arose on the trunk and 1 each on the leg, arm, and scalp. Increased cellularity, nuclear atypia, and mitoses (range, 1 to 63/50 high-power fields) indicated transition to MPNST, classified as low grade in 5, intermediate to high grade in 1, and high grade in 3 cases, 1 of which exhibited heterologous angiosarcomatous differentiation. S-100 expression was quite strong and diffuse in the neurofibroma components and less extensive or weaker in MPNST. Follow-up, available for all patients (median, 80.5 mo, except 1 recent case), revealed that 1 patient developed local recurrence after 9 months; 1 with metastases at the time of initial diagnosis died 1 month after tumor resection. All other patients were alive without evidence of disease at 15 to 145 months (median, 83 mo). Diffuse-type neurofibroma may show transformation to MPNST in very rare instances. It is important to be aware of possible malignant change, requiring thorough sampling of resection specimens and long-term clinical follow-up of patients with unexcised lesions.

Cytogenetics of neurofibromas: two case reports and literature review

Only a few karyotypes of neurofibromas have been documented in the literature. In this report, we describe two new cases in which conventional cytogenetics demonstrated the presence of abnormal clones. Combining karyotypes of the nine previously reported cases, we found that the most frequent structural rearrangements involved chromosome 9p. Including the two cases reported here, 5/11 cases involved 9p, and four of these involved the 9p21 approximately p22 region.

Cellular Neurofibroma with Atypia Mimics Sarcoma: Report of a Case with Immunohistochemical Staining Pattern Analysis and Literature Review

A case of two sporadic cellular neurofibromas with atypia and one widespread hyalinization neurofibroma of the lumbar spine in a 51-year-old man without evidence of neurofibromatosis-1 is reported. Cellular neurofibroma with atypia is an unusual variant. The definite criteria for low-grade and high-grade malignant peripheral nerve sheath tumors as well as cellular neurofibroma are not well defined in the literature. The clinical significance of atypical cellular neurofibroma has rarely been systematically studied. To our knowledge, the concomitance of cellular architecture and cytologic atypia is rarely documented, and this is a rare report of atypical cellular neurofibroma. The recognition of this entity is of great importance to both pathologists and clinicians because atypical cellular neurofibroma is clever at masquerading both histologically and cytologically as a sarcoma; therefore, a precise diagnosis of this variant is essential because of the differences in treatment and clinical behavior between benignancy and malignancy. We also examined the immunohistochemical characteristics of CD34 positive cells and focal high expression of p53 up to 73% encountered in our case. To our knowledge, seldom have series or case reports elucidated this phenomenon.

Molecular cytogenetic analysis in the study of brain tumors: findings and applications

Classic cytogenetics has evolved from black and white to technicolor images of chromosomes as a result of advances in fluorescence in situ hybridization (FISH) techniques, and is now called molecular cytogenetics. Improvements in the quality and diversity of probes suitable for FISH, coupled with advances in computerized image analysis, now permit the genome or tissue of interest to be analyzed in detail on a glass slide. It is evident that the growing list of options for cytogenetic analysis has improved the understanding of chromosomal changes in disease initiation, progression, and response to treatment. The contributions of classic and molecular cytogenetics to the study of brain tumors have provided scientists and clinicians alike with new avenues for investigation. In this review the authors summarize the contributions of molecular cytogenetics to the study of brain tumors, encompassing the findings of classic cytogenetics, interphase- and metaphase-based FISH studies, spectral karyotyping, and metaphase- and array-based comparative genomic hybridization. In addition, this review also details the role of molecular cytogenetic techniques in other aspects of understanding the pathogenesis of brain tumors, including xenograft, cancer stem cell, and telomere length studies.

A reciprocal t(4;9)(q31;p22) in a solitary neurofibroma

Cytogenetic reports of solitary neurofibromas are rare and, to our knowledge, no clonal reciprocal translocations have been reported in these tumors. Reciprocal chromosome translocations have been identified in a number of solid tumors and can have both diagnostic and prognostic significance. We report the first case of a solitary circumscribed neurofibroma with a (4;9)(q31;p22) balanced reciprocal translocation as the sole cytogenetic abnormality.

Genetics of Neurofibromatosis 1-Associated Peripheral Nerve Sheath Tumors

Neurofibromatosis 1, an inherited disorder that affects 1/3500 individuals worldwide, predisposes to the development of benign and malignant peripheral nerve sheath tumors. The disorder results from inactivation of one of the NFI genes. The second NFI gene is typically inactivated in Schwann cells during tumor formation. This article reviews the different types of genetic alterations in NFI in both constitutional and tumor tissues and genetic alterations of other genes that may affect tumorigenesis. These studies have provided insight into the genetic basis of both the variable expression of the disorder and of benign and malignant peripheral nerve sheath tumorigenesis.

Diffuse neurofibroma on the lower back

Diffuse neurofibroma is an uncommon form of neurofibroma, which occurs principally in children and young adults. This tumor presents most often in the head and neck region. We have seen a young girl with a diffuse neurofibroma on the lower back that was successfully excised.