Search

Background: Molluscum contagiosum (MC) is the commonest human poxvirus infection. Follicular induction has rarely been observed in the epidermis surrounding lesions of MC. A virus-induced localized proliferation of germinative/stem cells of the folliculosebaceous-apocrine unit has been suggested as the underlying cause, however few reports of this peculiar phenomenon exist in the literature and the mechanisms involved in this proliferation require further study., Methods: We prospectively collected MC cases showing multifocal areas of primitive follicular induction involving the adjacent undersurface epidermis. Immunohistochemical expression of BerEP4, PHLDA1 and cytokeratin 20 (CK20) was evaluated in the basaloid germs surrounding the lesions. For PHLDA1, we used epidermal melanocytes as a positive internal control. For BerEP4, we employed a basal cell carcinoma (BCC) and for CK20, colon as positive external controls. An incubation without the primary antibody functioned as an external negative control., Results: All the cases studied showed an intense positive staining of the basaloid buds with BerEP4 and weaker stain for PHLDA1. CK20 showed the presence of scattered Merkel cells within the induced epidermal basaloid proliferations favoring their reactive origin., Discussion: The pathogenetic mechanisms behind the development of these microscopic features and the link between follicular induction and poxvirus infection are explored. Awareness of this unusual phenomenon by dermatopathologists will be helpful in avoiding a misdiagnosis of a superficial BCC in such cases., Conclusions: BerEP4 and PHLDA1 were consistently expressed in the areas of primitive follicular induction surrounding lesions of MC. CK 20 stained the Merkel cells present in the basaloid buds. All these findings support the reactive origin of this phenomenon, which we believe is most probably viral-induced., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Amyloid is characterized by its fibrillary ultrastructure, and more than 20 proteins have been described to date as possible precursors. Among them, insulin and enfuvirtide represent the only medications described as amyloidogenic substances. We describe two diabetic patients, who were undergoing long-standing subcutaneous insulin treatment, who developed subcutaneous nodules at the sites of insulin injections. Histopathologic examination showed the presence of eosinophilic and amorphous masses in deep dermis, which stained positive with Congo red, amyloid P substance and anti-human insulin antibody. Whether the type of injected insulin played a role or not in the pathogenesis of the process is still uncertain, because all described patients used both fast-acting and slow-acting insulins at the same injection sites. Our second case showed nodular insulin-derived amyloid tumors only at the sites where exclusively fast-acting insulin was injected, which supports the notion that fast-acting insulin may also be the cause of this disorder. Insulin-derived nodular amyloidosis is probably underdiagnosed because of the small body of literature in comparison with the prevalence of insulin dependent diabetic patients. This underdiagnosis probably is because of its clinical similarity with the lesions of lipohypertrophy at the sites of insulin injections, which is rarely biopsied., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Merkel cell carcinoma (MCC) has been reported in association with other types of cutaneous neoplasms within the same lesion, including squamous cell carcinoma, Bowen's disease, actinic keratosis, follicular cysts, trichoblastoma and lentigo maligna, among others. However, the association of MCC and sweat gland tumors has never been described in the literature. We report two unique cases of MCC that developed within cutaneous poromas. A 56-year-old male (Patient 1) and an 81-year-old female (Patient 2) presented with nodules on the upper arm and lower back, respectively. Histopathologic study of both cases revealed a tumor in the dermis composed of poroid and cuticular cells intermingled with a proliferation of small round cells that showed characteristic histopathological and immunohistochemical features of MCC. In both cases, the two neoplasms were tightly admixed and distinct, suggesting that the MCC could have developed within a previously existing poroma. No morphological features of transition between the two tumors were seen. Neoplastic cells of MCC expressed immunoreactivity for chromogranin, synaptophysin, neuron-specific enolase, CAM 5.2 and cytokeratin 20, the last two markers showing the characteristic paranuclear dot-like pattern. In contrast, the poroma cells only expressed cytokeratin MNF116. Metastatic deposits were not identified in the regional lymph nodes or distantly., (© 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)