Cystic hamartoma of the renal pelvis.

We describe three hitherto undocumented cases of renal lesion in the adult age group that share a similar site and histological features. They are three adult women, with a short clinical history of pain and an abdominal mass. A partial or complete nephrectomy resulted in clinical cure. All cases showed an intrarenal multicystic mass situated adjacent to the pelvicalyceal system. These vaguely circumscribed lesions had no true capsule and blended in with the adjacent renal parenchyma. The histological appearance was distinctive and characterised by disorderly biphasic proliferation of epithelial and mesenchymal elements. The epithelial component consisted of tubules and cysts lined by cuboidal and columnar epithelium showing focal oncocytic changes. The stroma was cellular and predominantly fibroblastic with scattered bundles of smooth muscle cells. Despite extensive sampling, blastemal cells were not identified. The tubular epithelium was positive for CAM 5.2, epithelial membrane antigen, carcinoembryonic staining, and vimentin immunostaining. The stroma stained positively for vimentin and smooth muscle bundles for alpa smooth muscle actin and desmin. The cytological appearances of these lesions were benign. We propose that these are benign hamartomatous lesions arising as a result of faulty focal embryogenesis. They are distinct from well recognised lesions such as multilocular cysts, partially differentiated nephroblastomas, mesoblastic nephromas, and nephrogenic adenofibromas.

Low-grade primary B-cell lymphoma of the lung. An immunohistochemical, molecular, and cytogenetic study of a single case.

A case of primary low-grade pulmonary lymphoma is described. The histologic features conformed to those laid down by Saltzstein for a diagnosis of "pseudolymphoma." However, the immunocytochemical and molecular investigations confirmed the tumor to be a low-grade B-cell lymphoma of mucosa-associated lymphoid tissue (MALT). Cytogenetic studies revealed an abnormal karyotype with a translocation t(1;14). This is the first reported case of an abnormal karyotype in a case of a lymphoma of MALT.

The differential diagnosis of epithelial-type mesothelioma from adenocarcinoma and reactive mesothelial proliferation.

Three monoclonal antibodies (mAbs) have been applied to 14 adenocarcinomas, eight mesotheliomas, and nine reactive mesothelial proliferations. One of these, AUA1, is a novel antibody in this context. It was found in 13/14 of the adenocarcinomas but not in benign or malignant mesothelial tissue, making it a potential substitute for carcinoembyronic antigen (CEA) in the differential diagnosis of mesotheliomas from adenocarcinomas. In addition, the lesions were stained using an argyrophil technique to identify nucleolar organizer regions. The results of counting these showed a small but significant overlap in their numbers between malignant and benign mesothelial proliferations. Although there was a difference overall in the numbers of nucleolar organizer regions in adenocarcinomas and mesotheliomas, on the one hand, and benign hyperplasias, on the other, this overlap considerably reduces their value in assessing individual difficult cases.

Paratesticular sarcomas revisited: a review of cases in the British Testicular Tumour Panel and Registry.

OBJECTIVE: To assess differences in the histopathological diagnoses of a series of paratesticular sarcomas following changes in the morphological classification of these tumours and the availability of investigations to define their immunophenotype, and to consider the impact of these changes on clinical management. MATERIALS AND METHODS: Thirty-six soft tissue tumours of the paratesticular region, originally submitted to the British Testicular Tumour Panel and Registry between 1958 and 1967 were re-examined histologically using modern diagnostic criteria, including immunohistochemical features. Where possible, follow-up was brought up to date. RESULTS: Thirteen (35%) of the diagnoses made in 1967 were changed; of these, seven changes were attributable to the results of immunohistochemical tests and one involved the identification of an entity not recognized in 1967 (spindle cell rhabdomyosarcoma). CONCLUSION: The changes in diagnoses of major clinical relevance involved three neoplasms (8%) in which the recent opinion was rhabdomyosarcoma, a tumour for which successful treatment protocols are currently available.

Morphology and immunohistochemistry of carcinoma in situ adjacent to testicular germ cell tumours in adults and children: implications for histogenesis.

Observations differ on the pre-invasive malignant lesions associated with the various categories of testicular germ cell tumours. Such lesions have been found to be similar in appearance and are assumed to be composed of multipotent cells, or conversely a distinctive pre-invasive stage has been reported in association with each form of germ cell neoplasm. This study was undertaken to see whether distinctive morphological and immunohistochemical features of carcinoma in situ adjacent to various categories of germ cell tumours could be established. Carcinoma in situ adjacent to seminomas, teratomas and mixed germ cell tumours in 18 adults was indistinguishable morphologically. Placental alkaline phosphatase was demonstrated immunohistochemically but vimentin and low molecular weight cytokeratins were uniformly absent in these abnormal germ cells from all three groups. These findings support the concept of a multipotent pre-invasive malignant cell for both seminoma and teratoma in the adult. Carcinoma in situ was not seen adjacent to 15 spermatocytic seminomas, nor was placental alkaline phosphatase demonstrated in tubules adjacent to these tumours. These negative findings are additional evidence that spermatocytic seminoma differs from classical seminoma in its histogenesis. Carcinoma in situ, as defined morphologically and immunohistochemically in adults, was not identified adjacent to yolk sac tumours and differentiated teratomas in 20 prepubertal testes. The possibility that pre-invasive malignancy in children may not resemble that in adults must be considered when assessing the malignant potential of cryptorchid testes on biopsies taken during orchidopexy.

Symptomatic cysts in otherwise normal lungs of children and adults.

The clinical and pathological features of 28 lung cysts resected in the period 1980-1989, excluding those from patients with emphysema elsewhere in their lungs, have been reviewed. In 12 children aged 8 days to 17 years, five cysts were congenital adenomatoid malformations, three were bronchogenic cysts, two were intralobar sequestrations, one was a cystic haemangioma and one resembled the cysts excised from 16 adult patients. This latter group ranged in age from 20 to 62 years and included 11 cigarette smokers and five asthmatics. Twelve of these cysts were intralobar and four were attached by a pedicle to the pleural surface of the lung. All these cysts had a fibromuscular wall showing varying degrees of acute and chronic inflammation. The presence of at least a partial lining of epithelial cells in all the cysts was confirmed using an immunocytochemical marker. The surrounding lung did not show any significant pathology. These cysts are labelled as simple fibromuscular pulmonary cysts. In the childhood cases, a congenital cause could be established in the majority. The pathogenesis of the adult cysts remains unclear. The presence of inflammation in the cyst walls does not necessarily suggest a role for infection, as secondary infection of cysts cannot be ruled out. An aetiological role for local damage due to cigarette smoking or asthma must be taken into consideration.