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Background: Angiofibromas occur sporadically, and they develop in most patients with tuberous sclerosis complex (TSC), which is associated with alterations of the tumor suppressor genes TSC1 or TSC2. Loss of tuberin, the protein product of TSC2, has been shown in the interstitial fibroblast compartment of TSC-associated angiofibromas. It is unclear whether there is also a loss of hamartin, the product of TSC1 in TSC-associated and sporadic angiofibromas. Methods: The expression of hamartin and tuberin was analyzed by immunohistochemistry in 59 TSC-associated and 12 sporadic angiofibromas using affinity-purified antibodies. Results: Loss of expression of both tuberin and hamartin was detected in 14 angiofibromas, loss of only tuberin in three, and loss of only hamartin in four TSC-associated angiofibromas; but there was no loss in the sporadic angiofibromas. Only the interstitial cells, but not the vascular cells, showed a loss of expression of tuberin or hamartin. Conclusions: Loss of tuberin or hamartin occurred in a minority of the TSC-linked angiofibromas, but not in the sporadic angiofibromas. The absence of both tuberin and hamartin in some of the tumors suggests that the stability of tuberin and hamartin, which are believed to form an active complex in vivo, is negatively affected by the absence of either of the partners.

Background: Patients affected with tuberous sclerosis complex (TSC) are prone to the development of multiple benign tumors of the skin and other organs. Tuberin, the protein product of the tuberous-sclerosis-complex-2 tumor suppressor gene (TSC2) has been shown to inhibit cell proliferation. In TSC associated kidney tumors and sporadic brain tumors the loss/reduction of tuberin has been shown. Methods: Specimens of nine squamous cell carcinomas (SCC) and five basal cell carcinomas (BCC) from patients without TSC and six biopsies of connective tissue nevi (CTN) of patients with TSC were obtained. Specimens were analyzed by immunoblotting for the expression of tuberin. Results: Absent or reduced levels of tuberin were detected in the dermal parts of three of six shagreen patches, two of five BCC, and four of nine SCC. Conclusions: In tumors/hamartomas of patients with TSC the complete loss of TSC2 and tuberin is a mechanism which could be shown for CTN, thereby excluding the possibility of haploinsufficiency of TSC2. In a substantial number of cutaneous BCC and SCC the loss or downregulation of tuberin seems to be epigenetic, as alterations of TSC2 are not known in these tumors. The absence or reduction of tuberin might contribute to their proliferation.

Background: Tuberous sclerosis complex (TSC) is an autosomal dominantly inherited disorder associated with an alteration of the TSC2 tumor suppressor gene which encodes for the protein product tuberin. The disease is characterized by the development of hamartomas, e.g. cutaneous angiofibromas which consist of vascular cells, interstitial cells, and normal components of the skin. The Eker rat model, an animal model of inherited cancer, has been shown to carry a mutation of TSC2. Methods: Immunohistochemical analyses of human angiofibromas were performed using antibodies directed against tuberin and angiogenic growth factors. Proliferation of human dermal microvascular endothelial cells (HDMEC) was determined after incubation with the supernatants of TSC2 (+/+) and TSC2 (−/−) rat embryonic fibroblasts (REF) that were derived from the Eker strain. Results: Loss of the expression of tuberin was observed in the interstitial cells of 13 of 39 angiofibromas. The expression of tuberin was retained in the vascular cells. In all analyzed angiofibromas, the angiogenic factors bFGF, PD-ECGF, VEGF and angiogenin were detected in the interstitial cells and/or vascular cells. Expression of PDGF-B and TGF-β1 was weak. Tissue culture supernatants from TSC2 (−/−) REF stimulated the growth of HDMEC significantly more than supernatants from TSC2 (+/+) REF. Conclusion: A functional loss of tuberin may stimulate vascular growth.

A 19-year old patient with tuberous sclerosis presented with a renal angiomyolipoma. Because animal trials of tuberous sclerosis showed an effect of rapamycin on renal tumors, our patient was administered rapamycin for 6 months. During this time, the renal angiomyolipoma shrank significantly, regrew during an 8-month period, and decreased in size again after readministration of rapamycin.

Mutation of the p53 gene and increased levels of p53 protein are among the most frequent alterations in human cancers. To date, very little is known about the mechanisms underlying the development of sweat gland carcinomas. In this study, we analyzed 43 benign and 39 malignant sweat gland tumors for p53 protein level using the antibody PAB1801. Nine (23%) of 39 sweat gland carcinomas were positive for p53 protein. Among these carcinomas, six of 12 cases of extramammary Paget's disease were positive using immunohistochemistry. No other correlation between tumor subtype and p53 reactivity was detected. Among 43 benign sweat gland tumors, only one case displayed staining for p53. We conclude that p53 protein plays a role in a subset of sweat gland tumors, especially in extramammary Paget's disease.

A system for the detection of a Borrelia burgdorferi (Bb)-specific gene segment in formalin-fixed, paraffin-embedded skin lesions is described. A nested polymerase chain reaction technique is used to selectively amplify in vitro a short segment of a Bb-specific gene recently described by Rosa et al. (J Infect Dis 1989: 160: 1018). The design of oligonucleotide primers for the amplification of a relatively short gene segment allows the successful analysis of DNA which has been altered by fixation in formalin. Using this technique, Bb-specific DNA was clearly identified in 8 of 12 specimens of erythema chronicum migrans and in 1 case of lymphadenosis benigna cutis. These skin lesions are known to represent cutaneous manifestations of Lyme disease. Negative control reactions, using DNA from borrelial strains not related to Lyme disease, were negative. The system enables the dermatopathologist to identify Bb in routinely fixed clinical specimens and allows the rapid analysis of various skin diseases for which an association with Bb so far has only been hypothesized.

A series of 25 cutaneous B-cell lymphoid proliferations was analyzed for the presence of the (14; 18) translocation using the polymerase chain reaction. Junctional sequences of rearranged chromosomes 14 and 18 were amplified in vitro, and t (14; 18) specific sequences were detected in 1 of 14 primary cutaneous B-cell lymphomas, in 3 of 8 primary nodal B-cell lymphomas and in none of 3 B-cell pseudolymphomas. These results indicate that the t (14; 18) may occur in a small subset of primary cutaneous lymphoma. However, the difference in incidence of the t (14; 18) between primary nodal and primary cutaneous lymphomas suggests that different molecular mechanisms are involved in the pathogenesis of these lymphomas.

Individuals affected with tuberous sclerosis complex (TSC) develop several benign and malignant tumors at increased frequency, including astrocytomas. Tuberin, the protein product of the tuberous sclerosis complex-2 (TSC2) tumor suppressor gene, has been shown to directly inhibit cell growth and is expressed at high levels in normal central nervous system neurons and astrocytes. To determine whether TSC2 RNA and protein are reduced in astrocytomas from individuals without tuberous sclerosis, reverse transcriptase-polymerase chain reaction and immunoblotting analyses were performed on 49 adult astrocytomas, 10 pediatric astrocytomas, and 13 ependymomas. Eighteen of 40 (45%) high-grade (World Health Organization [WHO] grade III/IV) astrocytomas and 4 of 8 (50%) adult low-grade (WHO grade II) astrocytomas demonstrated reduced or absent TSC2 expression, including 1 giant cell astrocytoma, whereas none of the 10 pediatric low-grade astrocytomas analyzed showed a reduction in TSC2 expression. Reduced or absent tuberin was observed in 2 of 6 (33%) ependymomas analyzed. These data demonstrate, for the first time, that reduced or absent TSC2 expression may represent one of the critical genetic events associated with the development of sporadic adult, but not pediatric, astrocytomas.

We report an autopsy case of tuberous sclerosis complex (TSC) in a 20-week gestational age female fetus. The brain showed lesions suggestive of early cortical tubers and subependymal hamartomatous nodules. The large cells within these nodular clusters were variably immunoreactive for glial fibrillary acidic protein (GFAP) and vimentin and negative for synaptophysin and neurofilament. Subependymal radial glia expressed both vimentin and GFAP, but subpial radial glia either did not express these markers (in contrast to an age-matched control) or were absent. Tuberin expression was noted in heterotopic neurons in the white matter and brain cells consistent with Cajal Retzius cells in the neocortical molecular layer, very weakly in superficial cortical neurons, neurons in the basal ganglia, Purkinje cells and external granular cells of cerebellum, cranial nerve nuclei neurons, occasional germinal matrix cells, ependymal cells, choroid plexus epithelium, and pituitary gland neuroendocrine cells; it was not seen within the cells of subependymal nodules. The pattern of tuberin immunoreactivity was similar to that which we have observed in older TSC patients. Proliferating cell labeling indexes were comparable in the germinal matrix of the TSC patient and an age-matched control. Abnormal subpial radial glia may be responsible for some of the neuronal migration abnormalities that appear to result in neocortical tubers.

Tuberous sclerosis (TSC), an autosomal dominant disorder, is characterized by malformations, hamartomas and tumors in various organs including the brain. TSC is genetically linked to two loci: TSC1 on chromosome 9q34 and TSC2 on 16p13.3. TSC2 has been cloned, sequenced and encodes a protein (tuberin) which functions as a tumor suppressor. We have analyzed the distribution of TSC2 mRNA and tuberin in the brains of TSC patients and non-affected individuals using both autopsy and biopsy material. High levels of transcript and protein expression were observed in choroid plexus epithelium, ependymal cells, most brainstem and spinal cord motor neurons, Purkinje cells and the external granule cell layer of the cerebellum in both TSC and control cases. Individual balloon cells from TSC patients showed very faint expression while other glia showed no expression of either transcript or tuberin. Neocortical and hippocampal neurons expressed high levels of TSC2 transcript, but only modest levels of tuberin. The internal granule cell layer of the cerebellum expressed abundant transcript but low levels of tuberin. These observations suggest either that tuberin expression is controlled at the level of both transcription and translation or the antibody and in-situ hybridization recognize different splice variants of the TSC2 gene. In TSC patients, dysmorphic cytomegalic neurons expressed high levels of tuberin and transcript, particularly when in an 'ectopic' location. Individual cells within subependymal giant cell astrocytomas (SEGAs) and hamartomas from TSC patients expressed moderate to high levels of TSC2 transcript and tuberin. While the TSC2 transcript is widely expressed primarily within neurons, tuberin is demonstrable primarily within dysplastic/cytomegalic cells of the cortex and subependymal hamartomas/SEGAs. CNS expression of tuberin is unique in that primarily non-dividing cells express it in this location, whereas extra-CNS expression of tuberin is mainly found in actively proliferating cell types such as epithelium.

A possible association of Borrelia burgdorferi with localized scleroderma is currently the focus of intense research and discussion. Skin biopsies from 30 patients with localized scleroderma (28 of the plaque type/morphea; two linear scleroderma) were analyzed for the presence of Borrelia burgdoferi using three different polymerase chain reaction systems for amplification of segments of borrelial genes. Formalin-fixed, paraffin-embedded biopsies of 14 patients and fresh-frozen, cryo-conserved biopsies of 16 patients with localized scleroderma were obtained. Lesions of all patients showed clear signs of scleroderma and disease progression at the time of biopsy. Fresh-frozen as well as formalin-fixed biopsies from patients with erythema migrans or acrodermatitis chronica atrophicans were used as positive controls. With all three polymerase chain reaction systems, borrelial DNA was detected in none of the 30 specimens of localized scleroderma. In contrast, with one polymerase chain reaction system, Borrelia burgdorferi -specific DNA was found in 24 of 27 frozen biopsies from patients with erythema migrans and in all 5 analyzed frozen biopsies of patients with acrodermatitis chronica atrophicans. In approximately half of the paraffin-embedded biopsies from patients with erythema migrans (nine of 23) and acrodermatitis chronica atrophicans (13 of 27), Borrelia burgdorferi specific DNA was identified. These results question the association of localized scleroderma with known subtypes of Borrelia burgdorferi .

Molecular studies have substantially broadened our understanding of cutaneous lymphoproliferative disorders and have been introduced in the routine assessment of lesions suggestive of a lymphoma. As compared with traditional Southern blot analyses, PCR-based assays for the detection of monoclonal lymphoid populations in clinical specimens offer several advantages. In general, they are faster to perform and allow for the detailed molecular analysis of very small tissue specimens, including sections from formalin-fixed, paraffin-embedded biopsy specimens. The PCR-based assays for the analysis of CTCL involve the amplification of highly variable junctional sequences of rearranged TCR-gamma genes, which represent a unique molecular marker for an individual lymphoid cell and a clonal disease developing from this cell. Using various strategies and gel electrophoretic systems, the PCR products can be separated to detect subsets of identical amplification products representing identical gene rearrangements in a clonal lymphoid population in the analyzed specimen. Although the molecular evidence for a monoclonal cell population as provided by PCR technology is an important factor in the diagnosis of a cutaneous lymphoma, only the synopsis of all available clinical, histomorphologic, immunohistochemical, and molecular data will lead to the adequate assessment of a cutaneous lesion.

Analysis of complementary RNA molecules of junctional regions of rearranged T-cell-receptor-gamma genes show a pattern of conformational polymorphisms which is specific for an individual lymphocytic clone. In a blinded study we analysed formalin-fixed, paraffin-embedded histological specimens from gastrointestinal lymphomas and control tissues (lymphomas: pleomorphic T-cell 10, anaplastic large cell [Ki1+] 9, centroblastic 5, immunocytoma 1, B-CLL 2, Hodgkin's 2, centroblastic-centrocytic 1, MALT [mucosa associated lymphoid tissue] 1, T-cell acute lymphoblastic leukaemia 1, non-lymphoid or polyclonal lymphoid tissues 5). Junctional regions of rearranged TCR-gamma genes were amplified by the polymerase chain reaction and the products were transcribed into cRNA. Conformational patterns of cRNA molecules were analysed by polyacrylamide gel electrophoresis. 13/20 T-lineage lymphomas and the T-cell acute lymphocytic leukaemia displayed a distinct cRNA band pattern, all B-lineage lymphomas and the non-lymphoid control tissues were negative. Only one case of nasopharyngeal (lymphoepithelial, Schmincke-Regaud) carcinoma showed a faint cRNA banding pattern. This novel and non-radioactive assay allows for the rapid detection and molecular characterization of clonal lymphoid populations in minute histological biopsy specimens.