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Matrical differentiation in basal cell carcinoma (BCC) is rare. Only nine cases have been described that showed typical diagnostic features of BCC, in addition to shadow cells indicating hair-matrix differentiation. These cases often present a diagnostic challenge due to confusion with pilomatrixoma or pilomatrix carcinoma. We present a case of BCC with matrical differentiation in a 78-year-old man. Immunohistochemical and molecular methods are used to differentiate this lesion from benign or malignant forms of pilomatrixoma. differentiation: a case study with analysis of beta-catenin.

Mutations in beta-catenin are present in benign pilomatrixomas. beta-catenin is a downstream effector in the WNT-signalling pathway, acting as a signal for differentiation and proliferation. Mutations in CTNNB1, the gene encoding beta-catenin, are present in a wide variety of benign and malignant neoplasms. We examined beta-catenin in a series of pilomatrix carcinomas (15 cases) by using immunohistochemistry and DNA sequencing of exon 3 from CTNNB1, and compared these to a series of benign pilomatrixomas (13 cases). All 11 pilomatrix carcinomas available for examination showed nuclear localization of beta-catenin and mutations in exon 3 similar to those demonstrated in benign pilomatrixomas. Two of 11 pilomatrix carcinomas showed significant nuclear accumulation of p53, whereas this was absent in all 13 benign pilomatrixomas. Expression of nuclear cyclin D1 was similar in both benign pilomatrixomas and pilomatrix carcinomas. Clinical follow-up from the 15 malignant cases reported in this study and by others indicates that wide excision offers superior control of local recurrence, compared to simple excision. Immunohistochemical and molecular analysis of beta-catenin reveals that both pilomatrix carcinomas and benign pilomatrixomas harbour mutations in beta-catenin. This implies a common initial pathogenesis and is compatible with the proposition that pilomatrix carcinomas may at least on occasion arise from their benign counterparts.

Aberrant p53 immunoreactivity has been found in skin pre-malignancies and dysplasias such as Bowen's disease and actinic keratoses. Vulval lichen sclerosus (LS) has been reported to be pre-malignant, with an association of vulval carcinoma in 3% to 6% of patients. In contrast, non-genital LS appears to have no malignant potential. In this immunocytochemical study, we investigated p53 expression in 10 cases of histologically proven vulval LS and 9 cases of non-genital LS using the murine monoclonal antibody Do-1 raised against recombinant human p53 which reacts with both wild-type and mutant p53. None of the vulval specimens had epithelial dysplasia or malignancy. Normal vulval (7 cases) and non-genital skin (5 cases) were used as tissue controls, respectively. The cell proliferation index was also studied using the MIB 1 monoclonal antibody which detects the cell-cycle associated Ki-67 antigen. The technique of microwave irradiation for antigen unmasking was employed on formalin-fixed and paraffin-embedded tissues. There was a significant increase in p53 immunoreactivity in vulval LS (32.13 +/- 15.11 epidermal cells per 100 basal cells) compared to normal vulval skin (7.52 +/- 5.04 epidermal cells per 100 basal cells) (p < 0.001), whereas the MIB 1 labelling index was lower in vulval LS (39.45 +/- 15.88 epidermal cells per 100 basal cells) than in normal controls (86.26 +/- 32.31 epidermal cells per 100 basal cells) (0.001 < p < 0.01). In contrast, there was no significant difference in p53 immunoreactivity or MIB 1 labelling index between non-genital LS and normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of the p53 tumor suppressor gene product was determined in keratoses and skin cancers associated with psoralen photochemotherapy (PUVA). An immunocytochemical study was employed using CM-1 (polyclonal) and Do-1 (monoclonal) antibodies to human wild-type p53. Thirty-two cutaneous lesions and 20 perilesional PUVA-irradiated skin biopsies were examined from 7 patients, all of whom had received more than 200 PUVA treatments and/or a cumulative UVA dose of greater than 1000J/cm2 as treatment for widespread plaque psoriasis. p53 immunoreactivity was seen in 7 of 15 squamous cell carcinomas (46.7%), 5 of 8 dysplastic keratoses (62.5%) and in no basal cell carcinomas or benign keratoses. The overall prevalence of p53 immunoreactivity in 46.2% of malignant or dysplastic PUVA-associated skin tumors is similar to that previously found by our group in comparable skin tumors from the general population. Most patients with lesions showing positive p53 immunoreactivity had, however, been exposed to additional risk factors before receiving PUVA therapy. p53 gene sequencing of PUVA-associated non-melanoma skin cancer (NMSC) may clarify whether p53 mutation contributes to the development of these tumors and whether this relates to PUVA therapy or prior carcinogen exposure.

We report the clinical, histological and ultrastructural features of juvenile colloid milium affecting a brother and sister. In this rare condition, translucent papules develop on sun-exposed areas of skin, with onset in childhood. Histologically and ultrastructurally, the papules consist of amyloid-like material derived from epidermal keratonocytes. A review of the literature suggests a possible genetic abnormality that leads to sun-induced degeneration of keratinocytes.

Thirty-eight solar keratoses from 32 patients were studied for expression of mutant p53 protein by an immunohistochemical technique. Twenty-eight of the 38 solar keratoses (73.7%) showed positive and variable nuclear labelling, whereas 10 specimens were immunonegative. The nuclear immunopositivity which was seen in all variants was mostly diffuse in distribution. The adjacent "normal" epidermis of 8 keratoses showed positive mutant p53 labelling. Eight of the keratoses were associated with invasive squamous cell carcinoma of which only two were immunopositive. Cytoplasmic labelling was never a feature. The study demonstrates that mutant p53 protein is commonly expressed in all variants of solar keratosis and that its expression correlates with atypical keratinocyte proliferation. It is proposed that the demonstration of mutant p53 in the adjacent normal epidermis may be a potential marker of early neoplastic transformation.

We report three patients with pemphigoid nodularis. Patients were females aged 76, 71 and 50 years, and all had features of bullous pemphigoid together with prurigo-like lesions at some stage of their illness. In two cases, nodular lesions preceded the onset of blistering by some months. Blisters arose on normal skin and in one patients also at sites of prurigo lesions. Routine histology of bullous lesions revealed the presence of subepidermal blisters. Electron microscopy performed in two cases confirmed the level of split to be through the lamina lucida. Direct immunofluorescence in all cases was positive, with linear basement membrane zone deposition of IgG and C3. Circulating IgG anti-basement membrane antibody was also detected in all patients, and in two, immunoblotting revealed a single antigen of 220 kD.

Epidermolysis bullosa (EB) refers to a group of hereditary mechano-bullous conditions, many of which are associated with chronic scarring. Several forms of the disease have been reported in association with cutaneous malignancy. We present a series of 10 EB patients (eight generalised recessive dystrophic EB, one dominant dystrophic EB, one non-lethal junctional EB) aged 24-55 years with a total of 29 squamous cell carcinomas (SCC). Three patients died from metastatic disease associated with invasive, poorly differentiated SCC. Six cases had multiple primary SCC, including three patients with simultaneous multifocal disease. Twenty-eight of the 29 SCC arose on the limbs. Histology revealed that most of the SCC were well or moderately differentiated (22/29). Unusual histological findings included two verrucous SCC, as well as a spindle cell (angiosarcoma-like) SCC. Most of the SCC developed in areas of chronic non-healing ulceration (10/29) or longstanding hyperkeratotic crusting (14/29). The dermis around or beneath the carcinomas was densely scarred, more so than in non-malignant areas. In some cases it was difficult to distinguish the clinical appearances of certain areas of chronic ulceration, scarring, and crusting typical of dystrophic EB from many of the SCC. This study underlines the need for constant vigilance for the development of carcinomas in this group of patients, the occasional diagnostic difficulty, and the potential for metastasis.

Dermatofibrosarcoma protuberans (DFSP) is a not uncommon low-grade cutaneous sarcoma of uncertain histogenesis, which typically arises in early to middle adult life. Traditionally, it is regarded as extremely uncommon in infants and children, and this diagnosis may therefore easily be overlooked in young patients. Eight such cases (representing 5.9% of the available DFSPs on file) are presented of which two were congenital. Age range at presentation was 14 months to 12 years. Five arose on the trunk. Most had originally been mistaken for unclassified sarcoma, a fibromatosis, or diffuse neurofibroma. The histologic features were entirely comparable to the more usual adult cases except that all had a plaque-like, rather than nodular, growth pattern. Short-term follow up has revealed no recurrences. DFSP is not so rare in childhood and warrants wider recognition in order to ensure appropriate treatment.

Dermo-epidermal separation through the lamina lucida is an essential technique for immunoblotting studies and for the diagnostic immunofluorescence of autoimmune bullous diseases. The most widely used methods of producing skin separation in the laboratory are suction blister induction and incubation in 1 molar sodium chloride. More recently the use of a proteolytic enzyme, thermolysin, has been described for this purpose. We examined the electron microscopic appearance of five suction blisters, five skin specimens separated by 1 M NaCl, and five treated with thermolysin. Both suction blister formation and treatment with 1 M NaCl resulted in a clean separation through the lamina lucida in all specimens examined. However specimens treated with thermolysin developed intra-epidermal separation in four cases without any lamina lucida separation in three. Suction blister formation was associated with hemidesmosome disruption. Incubation in 1 M NaCl remains the most reproducible, convenient, and reliable method of producing dermo-epidermal separation in the laboratory.

Thirteen cases of fibroma of tendon sheath have been reviewed. This lesion presents predominantly in middle-aged adults, particularly men, and usually arises in the dermis and subcutis of the extremities, most especially the hands. Histologically these tumours are always well circumscribed and may be lobulated. They are largely composed of interlacing bundles of hyalinised, hypocellular fibrous tissue with occasional more cellular areas. A constant feature is the presence of slit-like vascular channels. They are benign lesions with little tendency to recur and, although becoming more generally recognised are not yet familiar to dermatologists.