Primary peritoneal mesotheliomas in children: a clinicopathological and immunohistochemical study of eight cases.

AIMS: To present eight cases of primary diffuse peritoneal malignant mesothelioma in children <15 years old, with a discussion of the pitfalls of this diagnosis in the paediatric age group. METHODS AND RESULTS: The cases were selected based on the following criteria: (i) primary peritoneal neoplasms confined grossly or radiographically to the abdominal cavity; (ii) negative history of previous or another associated malignancy; (iii) histopathological confirmation. All patients (five female, three male) presented clinically with symptoms of abdominal pain, distention and ascites. Grossly, the tumours showed multiple, diffuse peritoneal nodules. Histologically, seven cases corresponded to epithelioid mesotheliomas and one case displayed biphasic (epithelioid and spindle) cellular proliferation. Immunohistochemical studies for cytokeratin (CK) 5/6, calretinin and low-molecular-weight CK (CAM5.2) showed strong cytoplasmic positivity in the neoplastic cells. Three patients were treated by chemotherapy. On clinical follow-up, four patients with epithelioid mesotheliomas were alive and well from 12 to 18 months after initial diagnosis; one patient with a mixed (biphasic epithelioid/sarcomatoid) mesothelioma died of tumour 24 months after diagnosis. CONCLUSIONS: Peritoneal malignant mesothelioma in children is a rare condition that can introduce difficulties in histopathological diagnosis.

Sclerosing poorly differentiated liposarcoma: clinicopathological, immunohistochemical and molecular analysis of a distinct morphological subtype of lipomatous tumour of soft tissue.

AIMS: To present eight cases of a distinctive morphological subtype of lipomatous tumour of soft tissue. METHODS AND RESULTS: The clinicopathological, immunohistochemical and molecular pathological features of these tumours were analysed. The tumours were characterized by dense stromal sclerosis containing singly scattered pleomorphic atypical cells with lipoblastic features. The tumours occurred in four women and four men, aged 39-90 years (mean = 63). They were located in the retroperitoneum, thigh, retropubic space, arm and spermatic cord. Four cases arose de novo and four cases presented as local recurrences of previously resected liposarcomas. MDM2 amplification and cyclophosphamide doxorubicin hydrochloride (adriamycin), vincristine and prednisolone (CHOP) translocation was studied in seven cases by fluorescence in situ hybridization. High-level amplification of MDM2 at 12q13-15 was observed in 4/7 cases. All cases were negative for the CHOP translocation; in one MDM2+ case, the CHOP gene showed amplification but no translocation. Three patients died from their tumours from 1 to 6 years after their last surgery with lung metastases. CONCLUSIONS: The tumours described appear to represent an unusual morphological variant of poorly differentiated liposarcoma associated with aggressive behaviour, and may represent a common end-stage pathway for various types of liposarcoma.

Tumoral, quasitumoral and pseudotumoral lesions of the superficial and somatic soft tissue: new entities and new variants of old entities recorded during the last 25 years. Part XII: appendix.

In an eleven part series published in Pathologica, we have presented various tumoral, quasitumoral and pseudotumoral lesions of the superficial and somatic soft tissue (ST), which emerged as new entities or as variants of established entities during the last quarter of a century. Detailed clinicomorphological and differential diagnostic features of approximately sixty entities were chosen on the basis of their clinical significance and morphologic distinctiveness. The series included fibrous and myofibroblastic tumors (e.g. solitary fibrous tumor, high grade classic and pigmented dermatofibrosarcoma protuberans, inflammatory myofibroblastic tumor and myofibrosarcomas), fibromyxoid and fibrohistiocytic neoplasms (e.g., Evans' tumor, phosphaturic mesenchymal tumor, inflammatory myxohyaline tumor), special adipocytic/vascular/and smooth muscle lesions (e.g., chondroid lipoma, Dabska's tumor, ST hemangioblastoma, lipoleiomyosarcoma), epithelioid mesenchymal malignancies of diverse lineages (e.g., epithelioid liposarcoma, proximal-type epithelioid sarcoma, neuroendocrine extraskeletal chondromyxoid sarcoma), ST Ewing's tumor and peripheral nerve sheath tumors (perineuriomas and pigmented and rosetting tumors of the schwannoma/neurofibroma group), extranodal dendritic or histiocytic proliferative processes (follicular dendritic cell sarcoma, Rosai-Dorfman disease, Castleman's disease, and plexiform xanthomatous tumor), and tumors with myoepithelial differentiation. The section devoted to selected pseudotumoral entities considered representatives of the hamartoma group (neural fibrolipomatous hamartoma, ectopic hamartomatous thymoma, rudimentary meningocele), metabolic diseases (amyloid tumor, nephrogenic fibrosing dermopathy, tophaceous pseudogout, pseudoinfiltrative parathyromatosis), stromal tissue reactions to trauma (fibroosseous pseudotumors of digits) and infections (bacillary angiomatosis), and normal organs (glomus coccygeum). To conclude the descriptive phase, supplementary material has now been collected and appended in an attempt to provide a quick digest of essential knowledge both for comparison and differential diagnosis. The data have been tailored to synthesize diverse sources, integrating clinical elements and references to articles that previously appeared in Part I ("Introduction"), Part II ("The List and Review of New Entities") and Parts III to XI ("Excerpta"). At the very least we hope this final part ("Appendix") will provide the reader with a useful tabular organization of ST lesions and a reference resource.

Diagnosis of thymoma.

The diagnosis of thymic epithelial neoplasm has been a topic of controversy for many years. Reasons for this include the lack of predictive value associated with the morphology of these tumours and the multiplicity of classification schemes and terminologies proposed over the years. Recently, a new classification schema was introduced by the World Health Organization (WHO) in an attempt to standardise nomenclature and facilitate the diagnosis of primary thymic epithelial neoplasms. This schema, although not originally intended as a new histological classification, but rather as a means for translating equivalent terms from the various existing classifications, has represented a major step forward in this direction. However, problems still exist with the WHO schema, particularly with some of the criteria for the various histological subtypes as well as with issues of interobserver reproducibility. For this reason, we favour using a much more simplified approach to the morphological classification of thymic epithelial neoplasms. A personal approach to the morphological diagnosis of thymoma is described, with a brief explanation for the rationale for simplifying the existing diagnostic categories.

Expression of CD30 (Ber-H2) in nasopharyngeal carcinoma, undifferentiated type and lymphoepithelioma-like carcinoma. A comparison study with anaplastic large cell lymphoma.

AIMS: Undifferentiated nasopharyngeal non-keratinizing carcinoma (UNPC), formerly known as lymphoepithelioma, frequently metastasizes at an early stage to regional lymph nodes and, thus, may be difficult to distinguish from Hodgkin's lymphoma (HL) or anaplastic large cell lymphoma (ALCL). CD30 expression is a useful diagnostic stain in both HL and ALCL, but its expression in UNPC deserves clarification. The aim of this study was to evaluate CD30 expression in UNPC and lymphoepithelioma-like carcinoma (LELC) from other anatomic locations and compare it with ALCL and squamous cell carcinoma (SCC). METHODS AND RESULTS: CD30 immunoreactivity was examined in 38 cases of primary or metastatic UNPC, six cases of LELC, 10 cases of SCC and seven cases of ALCL. CD30 immunoreactivity was observed in four of 38 (10.5%) cases of UNPC. CD30 staining was absent in all cases of LELC (0/6) and SCC (0/10). All cases of ALCL (7/7) were strongly positive for CD30. CONCLUSIONS: The majority of cases of UNPC are immunohistochemically negative for CD30; however, a small subset of cases expresses CD30 antigen. These findings provide additional evidence that CD30 expression is not restricted to neoplasms of lymphoid origin. This should be taken into consideration when interpreting CD30 immunohistology and the possibility of UNPC.

Chromophobe renal cell carcinoma with microcystic and adenomatous arrangement and pigmentation--a diagnostic pitfall. Morphological, immunohistochemical, ultrastructural and molecular genetic report of 20 cases.

We present clinical, morphological, immunohistochemical, ultrastructural and molecular genetic features of 20 cases of a peculiar form of chromophobe renal cell carcinoma (CRCC) with morphology differing from that of conventional CRCC. Microscopically, the typical features of the tumors were microcystic arrangement and formation of adenomatous structures. Microcystic areas were composed of smaller eosinophilic and bigger pale cells having cytological appearance typical of conventional CRCC. Cytological features of the adenomatous structures were mostly different from those of conventional CRCC. They had a typical columnar arrangement with nuclei positioned at the base of the glandular structures and a small amount of a deeply eosinophilic cytoplasm often endowed with brush border facing the lumen of the glands. In addition, all the tumors showed a brown pigmentation. The pigmentation was located mostly extracellularly, where it formed pools of heavy deposits. Microscopic calcifications present in all cases formed psammoma bodies or else the calcifications were more extensive and amorphous in shape. Ultrastructurally, the cells showed features characteristic of CRCC: typical cytoplasmic vesicles were 100-700 nm in size and mitochondria had tubulovesicular, lamellar or circular cristae. Some tumor cells contained dark, variously sized electron-dense pigment granules. Neither melanosomes nor membrane-bound neurosecretory granules were seen. Using fluorescence in-situ hybridization probes for chromosomes 1, 2, 6, 10, 13, 17 and 21, the tumors revealed massive loss of tested chromosomes typical for conventional CRCC. Monosomy of chromosomes 1, 2, 6, 10, 13 and 21 was found in 100, 36, 91, 82, 82, 82 and 64% of cases, respectively. None of the cases showed mutation of exons 9, 11, 13 and 17 of the c-kit gene. The important feature of pigmented microcystic chromophobe renal cell carcinoma is a relatively benign biological behavior and the absence of distant metastases and sarcomatoid transformation.

[Spindle cell and cuboidal renal cell carcinoma (loopoma). 10 case reports]. / Vretenobunecný a kuboidální renální karcinom (loopom). Popis 13 prípadu.

BACKGROUND: Current classification systems of neoplasms arising from renal parenchyma distinguish 5 categories of renal cell carcinoma (RCC), i.e. conventional RCC, papillary RCC, chromophobe RCC, collecting duct/medullary RCC and unclassified RCC. We present 13 cases of unusual and unclassified spindle and cuboidal renal cell carcinomas. METHODS AND RESULTS: The studied group consisted of 13 patients (7 men and 6 women). They ranged in age from 22 to 65 years (mean 57.3). Generally, the tumours were well circumscribed and confined to the kidney, whitish to grey on section with a diameter 4.5-13 cm (mean 8.6 cm). One patient was investigated for loin pain and nocturia. Three patients had staghorn nephrolithiasis and vague sonographic findings in renal parenchyma. In one patient the renal tumour was found when examined on follow-up examination for prostatic adenocarcinoma. None of our patients was known to have elevated levels of parathyroid hormone due to hyperplasia, adenoma or carcinoma of the parathyroid gland. Clinical follow-up of the patients ranged from 9 months to 8 years (mean 2.3 years). Microscopically, the tumours were composed of two main populations of cells: flattened, spindle cells with sparse cytoplasm and small cuboidal cells with clear to light eosinophilic cytoplasm. Eight patients are currently well without signs of recurrence or metastasis, one had metastasis in the regional lymph node at the time of nephrectomy, one died of unrelated cause, and three were lost to follow-up. CONCLUSIONS: We present 13 cases of unclassified RCC. Our cases were histologically, immunohistochemically and ultrastructurally similar to the hitherto reported case reports of this variant of RCC. It is obvious, that that variant of RCC should be recognised as a new subtype of RCC.

Carcinomas arising in multilocular thymic cysts of the neck: a clinicopathological study of three cases.

AIMS: To report three cases of primary carcinoma of the neck arising in multilocular thymic cysts (MTC). METHODS AND RESULTS: The patients were three men aged 47, 50 and 52 years who presented with a painless neck mass of several weeks' duration. The patients had no history of previous surgical procedures or of malignancy elsewhere. The tumours in all three patients were located on the right lateral side of the neck; all patients underwent complete surgical resection of the mass. Grossly, the tumours were cystic and measured between 20 and 30 mm in greatest diameter. Histologically, the tumours showed cyst walls lined by squamous epithelium. The cyst walls contained prominent germinal centres with lymphoid hyperplasia, cholesterol cleft granulomas, and scattered keratinized structures reminiscent of Hassall's corpuscles. In addition, a neoplastic cellular proliferation composed of round to oval cells arranged in sheets and originating from the lining of the cystic structures was present. The neoplastic cells showed moderate amounts of eosinophilic cytoplasm, round nuclei, and, in some areas, prominent nucleoli. Mitotic figures were easily found, and cellular pleomorphism was present in several areas. In two cases the tumours showed features of basaloid carcinoma of the thymus, while in one case the pattern was that of squamous cell carcinoma. Immunohistochemical studies for keratin showed a strong positive reaction in the tumour cells, while leucocyte common antigen strongly stained the lymphoid background. Follow-up information obtained in two patients showed them to be alive 6 months after initial diagnosis. One patient was lost to follow-up. CONCLUSION: The cases described here represent an unusual variant of carcinoma arising in multilocular thymic cyst in the neck region.