Clinical And Experimental Research Of Tuberous Sclerosis

Part 1: Cutaneous lesions and visceral involvement of tuberous sclerosisBackground: Tuberous sclerosis (TS) is an autosomal dominant disorder with a significant range of clinical expressions. The involvement of vital organs, such as brain, kidneys, heart and lungs is the main cause of death in the patients with TS. Objective: To summarize the charateristic cutaneous features and common extracutaneous involvement of TS which facilitate the clinicians to diagnose correctly and detect important visceral involvement early. Methods: The clinical data of 78 patients with TS were analyzed, including detailed history, physical and dermatological examination, cranial computerized tomography (CT) and magnetic resonance imaging (MRI), abdominal ultrasonography, chest roentgenogram, hand and foot X-ray and ophthalmologic examination.Results: The results showed that skin, brain and kidney were involved frequently in the TS patients. The hypomelanotic macules were most common and earliest cutaneous lesions. The number of hypomelanotic macules was more than 3 in 81.5% patients with them. Facial angiofibromas were seen next most often, and followed by Shangreen's patch. The mean age of appearance of forehead plaque, facial angiofibromas and Shagreen's patch was 2.6,6.0,8.1 years old respectively. Cranial CT scanning had a high positive rate in the TS patients. The disease has a tendency to be misdiagnosed and the diagnosis is often missed when the patients have only complaint of connective tissue nevus or subependymal giant cell astrocytomas or renal angiomyolipomas or epilepsy.Conclusions: The cutaneous features of TS are helpful in the early diagnosis of the disease. The clinicians should pay attention to the hypomelanotic macules in the patients especially with epilepsy or if the number is more than 3 in a baby. Cranial CT is of great value in the diagnosis of TS. The involvement of visceral organs such as brain and kidneys should be examined and followed up in the TS patients. The patients with connective tissue nevus on the lumbosacral area or subependymal giant cell astrocytomas of the lateral ventricle or renal angiomyolipomas should be suspected TS and the examination for other signs ofTS is needed.Part 2: Histological and immunohistochemical study of hamartomas associated with tuberous sclerosisBackground: Tuberous sclerosis (TS) is an autosomal dominant neurocutaneous syndrome characterized by various hamartomas involved the three embryonic layers. Objective: To investigate the pathological features of the hamartomas associated with TS and to assess these hamatomas have the common origin.Methods: 33 hamartomas associated with TS (including 20 skin lesions, 10 brain tumors, 2 renal tumors and 1 maxillary sinus tumor) were studied pathologically and immunohistochemically by the ABC method using antibody for GFAP, S-100, NF, Syn, HMB-45 and CD34. 20 skin specimens (8 facial angiofibromas, 10 Shagreen's patches and 2 forehead plaques) were further studied by Weigert' s elastic fiber stain. Some tumors were also studied immunohistochemically using antibody for SMA,CK, EMA and VIM.Results: 1. All 10 brain tumors are subependymal giant cell astrocytomas (SEGAs), 2 renal tumors are angiomyolipomas (AMLs), and 1 tumor of maxillary sinus is desmoplastic fibroma like tumor.2. CD34 was stongly positive in the TS associated lesions.3. Facial angiofibromas, Shagreen's patches and forehead plaques showed excess of collagen and decrease of elastic tissue.4. The cells of SEGAs associated with TS showed variable immunoreactivity for GFAP, S-100, NF and Syn whereas the skin lesions and the tumor of the maxillary sinus showed no immunoreactivity for them. GFAP, NF, and Syn were negative in the renal AMLs (angiomyolipomas) and S-100 was positive in the part of the fat cells of the renal AMLs.5. HMB-45 was positive in the smooth muscle cells of renal AMLs (angiomyolipomas) and some of the giant cells of SEGAs, but was negative in skin lesions and maxillary sinus tumor.Conclusions: 1.The TS associated lesions have distinct pathological and immunohistochemical features.2. The TS associated lesions are highly vascular.3. Excess of collagen and decrease of elastic tissue can be found in all the common cutaneous lesions of TS.4. The cells of the SEGAs exibit both glial and neronal epitopes and have the capacity of divergent differentiation.Part 3: Differences between the Shangreen patch associated with tuberous sclerosis and the connective tissue nevus without tuberous sclerosisObjective: To compare the Shangreen patch associated with TS and the connective tissue nevus without TS.Methods: 10 Shangreen patches with TS and 5 connective tissue nevi without TS have been studied pathologically and immunohistochemically by the Weigert's elastic fiber stain and ABC method using the antibody for GFAP, S-100, NF, Syn, HMB-45 and CD34.Results: The Shangreen patches associated with TS were always multiple and the connective tissue nevi without TS were often solitary. HE stain showed that collagen excess can be found in both the connective tissue nevi and the Shangreen patches. Small quantity of fat cells were found embedded among the collagen bundles in the former whereas not found in the latter. Elastic fiber stain showed that elastic fiber was decreased markedly in the upper dermis of the Shangreen patches, but it was increased or nomal or decreased in the connective tissue nevi without TS. The elastic fiber was well- distributed in the whole dermis when it was decreased. Both of them were negative for GFAP, S-100, NF, Syn and HMB-45. CD34 was expressed strongly both in the Shangreen patches and the connective tissue nevi without TS.Conclusions: The Shangreen patches associated with TS is different from the connective tissue nevi without TS although they share some common features. Elastic fiber stain is helpful for the differential diagnosis.Part 4: Mutational analysis of the TSC₁ gene in tuberous sclerosisObjective: To detect the gene mutation of the exon 15, 17, 18 in the TSC1 gene in patients with TS.Methods: Exon 15, 17, 18 of the TSC1 gene were analyzed by using PCR-DHPLC (polymerase chain reaction -Denaturing high performance liquid chromatography) in DNA separated from peripheral blood of 32 patients with TS and their parents.Results: The DHPLC elution profiles showed one variant in exon 18 in one patient and the mutation 2285A→G (762D→S) of exonl8 was further comfirmed by sequencing. The same mutation was also found in his father who had only hypomelanotic macules and cafe au lait. The mutation was not found in his mother and normal controls.Conclusions: A noval mutation 2285A→G(762D→S) of TSC1 was deteded by PCR-DHPLC-DNA sequencing which is a convenient method for TSC gene mutational analysis.