A Focus of Differentiated Myeloid Sarcoma in a Ligation Specimen of the Fallopian Tube: No Evidence of Hematologic Abnormality in 18 Years of Follow-up Despite Absence of Treatment.

A 0.2-cm intramural focus composed predominantly of myelocytes and metamyelocytes, many CD3+, CD43+ T-lymphocytes, scanty CD20+ B-lymphocytes, rare mast cells, but no eosinophils or myeloblasts was incidentally found in a ligation specimen of the left fallopian tube. The myeloid cells were positive for chloroacetate esterase, myeloperoxidase, myeloid marker BM2, and CD43, and they were negative for CD30, CD34, CD117, ERG, and TDT. The findings in the left fallopian tube were consistent with the diagnosis of differentiated myeloid sarcoma. The right fallopian tube was normal. No hematologic abnormalities were found elsewhere in the body. Curiously, the patient remains free of any hematologic abnormality for 18 years despite absence of treatment.

Oncocytic Melanoma: A Study of a Rare Entity.

The authors report the second case of oncocytic melanoma, one of the rarest known melanoma variants. The diagnosis was established by Fontana stain positivity, expression of S100 protein as well as gp100/HMB45, and demonstration of numerous mitochondria by ultrastructure. Because it is known that some oncocytic tumors of the thyroid gland and kidney contain point mutations and common deletions of mitochondrial DNA, the complete mitochondrial DNA of the reported oncocytic melanoma was also studied. It was normal except for 2 private separate point mutations, predicted to be not pathogenic, which do not seem to play any role in the tumor phenotype.

Rhabdoid Myomelanocytic Tumor (PEComa) of the Ovary: A Clinically Benign Case Followed for 7 Years.

A 3.0 × 2.5 cm rhabdoid myomelanocytic tumor was incidentally found in the left ovary of a 43-year-old black woman. The tumor cells were cytologically bland with minimal proliferation rate, multifocally weakly or moderately expressed TFE3, strongly expressed smooth muscle markers and SMARCB1/INI1, and focally expressed HMB45. They contained numerous paranuclear whorls of intermediate filaments that were verified by ultrastructure. No other lines of differentiation were detected within the tumor. Neither translocation nor increased number of copies of the TFE3 gene at Xp11.22 was detected by fluorescence in situ hybridization. The patient remains well, free of tumor, 7 years after surgery. A rhabdoid variant of myomelanocytic tumor is a rarity, with only a single case described previously.

Thymic Tumor With Adenoid Cystic Carcinoma-Like Features: A Study of a Clinically Favorable Case Followed for 9 Years.

Thymic tumors with adenoid cystic carcinoma-like features are true rarities, with only 6 cases reported. Our knowledge of their clinical behavior is insufficient. We present a case of a noninvasive cribriform tumor that was followed, including a 4-year period after tumor resection and radiation therapy, for a total of 9 years. The tumor was purely epithelial. It was positive for keratins (AE-1/AE-3, CK19, 34ßE12,CK5/6), MOC-31, P63, P40, CD10, and MYB, and was negative for myoepithelial or neuroendocrine markers. Presence of cell processes, desmosome-like junctions with tonofilaments and multifocally reduplicated basal lamina was noted on ultrastructural examination. Two signals of the MYB gene per cell were detected by fluorescence in situ hybridization. No monosomy or translocations of the gene were found. Although additional clinical studies are necessary, it seems that indolent behavior of cribriform noninvasive subset of these tumors may be anticipated.

Large lymphaticovenous malformation resection.

We report a case of a giant cardiac lymphaticovenous malformation arising from the atrioventricular groove in a 38-year old Caucasian female. Cardiac vascular lesions are rare and tend to be poorly described in the literature. Lymphaticovenous malformations are present at birth and develop due to errors in venolymphatic development. As the tumour enlarged, the patient experienced significant shortness of breath on exertion. At resection, the mass measured 6.0 cm anterior-posterior ×10.4 cm craniocaudal. The mass was found to be adhered tightly to the coronary sinus. Histologically, the lesion was composed of dilated vascular and lymphatic channels within a fatty stroma. The mass was resected without complications.

Unusual histologic variant of a low-grade fibromyxoid sarcoma in a 3-year-old boy with complex chromosomal translocations involving 7q34, 10q11.2, and 16p11.2 and rearrangement of the FUS gene.

Low-grade fibromyxoid sarcomas are rare, histologically deceptive, cytologically bland tumors that are infrequently encountered in pediatric patients. Our knowledge of histologic spectrum of these tumors is limited. A histologically unusual variant of a low-grade fibromyxoid sarcoma arising in a 3-year-old boy and containing islands of cohesive epithelioid cells is described. The diagnosis was, given the patient's age and the presence of epithelioid islands, very difficult and was verified by the presence of 3-way chromosomal translocations involving 7q34, 10q11.2, and 16p11.2 by rearrangement of the FUS gene and by immunoreactivity for mucin 4.

SMARCB1 protein and mRNA loss is not caused by promoter and histone hypermethylation in epithelioid sarcoma.

About 10% of epithelioid sarcomas have biallelic mutation of the SMARCB1 (SWI/SNF-related, matrix-associated, actin-dependent regulator of chromatin, subfamily b, member 1) gene resulting in a lack of this nuclear protein. It has been suggested that SMARCB1 may be silenced by epigenetic changes in the remaining 90% of tumors. Thus, we hypothesized that the promoter of SMARCB1 is hypermethylated. We also examined SMARCB1 mRNA level to determine if a post-translational change was possible. Thirty-six cases of epithelioid sarcomas were studied. Immunohistochemistry and mutation analysis of the SMARCB1 gene were performed to select appropriate cases. Methylation status was assessed by methylation-specific PCR. Laser capture microdissection of tumor cells followed by real-time PCR was applied to examine the expression of SMARCB1 mRNA. Of 36 epithelioid sarcomas, 31 (86%) displayed a lack of SMARCB1 nuclear protein. In all, 4 (13%) of 31 SMARCB1-negative cases harbored biallelic deletion while 9 (33%) cases showed single-allelic deletion. One (4%) frameshift deletion of exon 3 and one point mutation of exon 7 were also found. In 16 (59%) cases, both alleles were intact. Altogether, 25/31 (81%) SMARCB1-negative cases had at least one intact allele. None of these cases demonstrated promoter hypermethylation. Low levels of SMARCB1 mRNA were found in all cases with tumor tissue extracted RNA (because of the minimal normal cell contamination) but no mRNA could be detected in laser dissected cases (containing only tumor cells). Enhancer of zeste homolog 2 (EZH2) overexpression was not characteristic of epithelioid sarcoma. Thus, loss of SMARCB1 expression in epithelioid sarcoma is caused neither by DNA hypermethylation nor by post-translational modifications. Most likely it is the microRNA destruction of SMARCB1 mRNA but further investigations are needed to elucidate this issue.

Uterine neuroectodermal tumor with ependymoblastic features in an infant with clonal +del (2)(q11.2),-13: a possible role of increased gene dosage on 2pter-2q11.2 in the tumorigenesis.

Clonal +(2)(q11.2),-13 was detected in a uterine neuroectodermal tumor with ependymoblastic features arising in an infant. The tumor expressed vimentin, nestin, CD56, CD99, microtubule-associated protein 1B (MAP 1B), focally microtubule-associated protein 2 (MAP 2), synaptophysin, neuron-specific enolase, and, very focally, epithelial membrane antigen. Because trisomy 2 was previously detected in a medulloepithelioma of pelvic soft tissue and in several neuroectodermal tumors of the central nervous system, this finding is indicative of a possible role of increased dosage of gene(s) on chromosome 2 in the tumorigenesis of these neoplasms and of their histogenetic relatedness.

CD99-positive large cell neuroendocrine carcinoma with rearranged EWSR1 gene in an infant: a case of prognostically favorable tumor.

The first case of large cell neuroendocrine carcinoma arising in an infant is presented. The tumor arose at the anal verge of a 1-year-old girl. The diagnosis of this CD99-positive tumor was supported by expression of epithelial (keratins, EMA, and Ep-CAM) and neuroendocrine (chromogranin A, synaptophysin, and neuron-specific enolase) markers and absence of immunoreactivity for Fli-1. No fusion of EWSR1 with FLI-1 or ERG was detected by polymerase chain reaction. However, the split of the EWSR1 gene was demonstrated by fluorescence in situ hybridization. This case adds to the few epithelial tumors in which an EWSR1 rearrangement was demonstrated. Because the tumor was initially misclassified as an extraskeletal Ewing's sarcoma, the patient was treated according to the Ewing's sarcoma treatment protocol. She remains free of tumor 8 years after initial diagnosis.

Pericentric inversion (12)(p12q13-14) as the sole chromosomal abnormality in a leiomyoma of the vulva.

We present a case of a leiomyoma of the vulva with karyotype 46,XX,inv(12)(p12q13-14). It is noteworthy that the breakpoint at 12q13 approximately q14 is flanked by the HMGA2 gene. Although the gene remained intact, the presence of HMGA2 protein in the neoplastic cells indicates that it became activated by the rearrangement. It is curious that activation of the HMGA2 gene, while not restricted to smooth muscle tumors, was so far found only in genital leiomyomata (uterus, vulva, vagina) and not in any smooth muscle tumors arising in extragenital locations.

An unusual self-limited clonal Mott cell proliferation with lymphoplasmacytic lymphoma-like features in a child with the Wiskott-Aldrich syndrome and Von Recklinghausen's neurofibromatosis.

Patients with the Wiskott-Aldrich syndrome are at high risk for development of lymphomas, which are predominantly extranodal and of the immunoblastic type. We present a case of a self-limited lymphoproliferation with features of lymphoplasmacytic lymphoma arising in a patient with the Wiskott-Aldrich syndrome. The patient also had stigmata of von Recklinghausen's neurofibromatosis. The tumor was composed of CD138+, IgGkappa+, CD20-, PAX-5- Mott cells and CD5-, CD10-, CD19+, CD20+, CD43- small lymphoid B-cells that partially expressed CD23. The lymphadenopathy spontaneously resolved after a period of less than a year, and the patient had remained free of detectable lymphoproliferation for almost 4 years. He then developed Burkitt's lymphoma of the left parapharyngeal space. It is remarkable that both known lymphoproliferations with features of lymphoplasmatic lymphoma arising in patients with the Wiskott-Aldrich syndrome, this one and the previously described one, have spontaneously resolved. This observation is truly intriguing and requires further clinico-pathologic studies.

Perineurioma of the adrenal gland.

The authors report the first case of perineurioma of the adrenal gland. The tumor was composed of elongated wavy spindle cells focally arranged in a fascicular pattern. It was positive for epithelial membrane antigen (EMA) and claudin-1, and was negative for S-100 protein and glial fibrillary acidic protein (GFAP). Electron microscopy showed long, slender cytoplasmic processes coated by discontinuos basal lamina and presence of many pinocytotic vesicles.

A comparative immunohistochemical analysis of small round cell tumors of childhood: utility of peripherin and alpha-internexin as markers for neuroblastomas.

Immunohistochemical study of neuroblastomas, Ewing sarcomas, rhabdomyosarcomas, and Wilms tumors demonstrate specific expression of peripherin and alpha-internexin in 20/22 and 6/22 cases of neuroblastomas, respectively. Microtubule-associated protein 1B (MAP 1B) was strongly and diffusely expressed in all 22 cases of neuroblastomas, but was also focally or multifocally expressed in 9/12 rhabdomyosarcomas and also in the blastema and stroma of 8/11 Wilms tumors. All rhabdomyosarcomas strongly and diffusely express nestin, but this marker was also expressed, multifocally, in 15/22 neuroblastomas and also in the blastema and stroma of all 11 Wilms tumors. NeuN, a neuron-specific nuclear protein, was expressed focally in 1 case of neuroblastoma and diffusely in 2 other cases (3/22). Surprisingly, it was also focally expressed in 2/12 rhabdomyosarcomas. In contrast, all 7 cases of Ewing sarcoma were negative for peripherin, MAP 1B, alpha-internexin, NeuN, and nestin. Thirteen neuroblastomas were also immunostained for neurofilaments, tyrosinase, and anaplastic lymphoma kinase 1 (ALK 1), and were found to be negative for these markers. Our results confirm that peripherin and alpha-internexin are neuroblastoma markers useful for the differential diagnostic work-up of small round cell tumors of childhood. Strong diffuse immunoreactivity for MAP 1B favors a diagnosis of neuroblastoma, whereas strong diffuse immunoreactivity for nestin favors a diagnosis of rhabdomyosarcoma.