Benign follicular tumors comprise a large and heterogeneous group of neoplasms that share a common histogenesis and display morphological features resembling one or several portions of the normal hair follicle, or recapitulate part of its embryological development. Most cases present it as clinically nondescript single lesions and essentially of dermatological relevance. Occasionally, however, these lesions be multiple and represent a cutaneous marker of complex syndromes associated with an increased risk of visceral neoplasms. In this article, the authors present the microscopic structure of the normal hair follicle as a basis to understand the type and level of differentiation of the various follicular tumors. The main clinicopathological features and differential diagnosis of benign follicular tumors are then discussed, including dilated pore of Winer, pilar sheath acanthoma, trichoadenoma, trichilemmoma, infundibuloma, proliferating trichilemmal cyst/tumor, trichoblastoma and its variants, pilomatricoma, trichodiscoma/fibrofolliculoma, neurofollicular hamartoma and trichofolliculoma. In addition, the main syndromes presenting with multiple follicular tumors are also discussed, namely Cowden, Birt-Hogg-Dubé, Rombo and Bazex-Dupré-Christol syndromes, as well as multiple tumors of follicular infundibulum (infundibulomatosis) and multiple trichoepitheliomas. Although the diagnosis of follicular tumors relies on histological examination, we highlight the importance of their knowledge for the clinician, especially when in presence of patients with multiple lesions that may be the cutaneous marker of a cancer-prone syndrome. The dermatologist is therefore in a privileged position to recognize these lesions, which is extremely important to provide further propedeutic, appropriate referral and genetic counseling for these patients.

The medical term onychomycosis should be understood as chronic infection of the nails caused by a fungus. The most common causative agents are the dermatophytes and Candida species. The less common are certain types of moulds (nondermatophyte moulds or NDMs). In approximately 60-80 % of the cases, onychomycosis is due to dermatophytes. Among dermatophytes, the most often isolated causative pathogen is Trichophyton (T.) rubrum. Other common species are T. interdigitale (formerly T. mentagrophytes), Epidermophyton floccosum, and T. tonsurans. The most significant yeasts causing onychomycosis are Candida albicans and Candida parapsilosis. Predisposing factors for onychomycosis include mainly diseases such as diabetes mellitus, peripheral vascular arterial disease, chronic venous insufficiency, polyneuropathies of diverse etiologies, and immunosuppression, e.g., myeloproliferative diseases (such as lymphoma and paraproteinemia), HIV/AIDS, etc. Other factors facilitating the fungal infection are frequent trauma in professional sportsmen, often accompanied by excessive perspiration. The diagnostic methods that are often applied in different dermatologic departments and ambulatory units are also different. This precludes the creation of a unified diagnostic algorithm that could be used everywhere as a possible standard. In most of the cases, the method of choice depends on the specialist's individual experience. The therapeutic approach depends mostly on the fungal organism identified by the dermatologist or mycologist. This review hereby includes the conventional as well as the newest and most reliable and modern methods used for the identification of the pathogens causing onychomycosis. Moreover, detailed information is suggested, about the choice of therapeutic scheme in case whether dermatophytes, moulds, or yeasts have been identified as causative agents. A thorough discussion of the schemes and duration of the antifungal therapy in certain groups of patients have been included.

Cutaneous adnexal tumours can be a diagnostic challenge for the pathologist. This is particularly true in the case of tumours with sweat gland differentiation, due to a large number of rare entities, a multiplicity of names to designate the same neoplasms and consequent lack of consensus regarding their classification and nomenclature. In the traditional view, sweat gland tumours were divided into eccrine and apocrine. However, this has been challenged in recent years, and in fact many of these tumours may have both eccrine and apocrine variants. Some display more complex features and defy classification, due to the presence of other lines of differentiation, namely follicular and/or sebaceous (in the case of apocrine tumours, due to the close embryological relationship between apocrine glands, hair follicles and sebaceous glands). The present paper reviews and updates the basic concepts regarding the following malignant sweat gland tumours: apocrine carcinoma, porocarcinoma, hidradenocarcinoma, spiradenocarcinoma, cylindrocarcinoma, microcystic adnexal carcinoma and related entities, squamoid eccrine ductal carcinoma, digital papillary adenocarcinoma, primary cutaneous mucinous carcinoma, endocrine mucin-producing sweat gland carcinoma and primary cutaneous signet ring cell carcinoma. Particular emphasis is put in recent findings that may have implications in the diagnosis and management of these tumours.

Pyoderma gangrenosum (PG) is a rare disease, but commonly related to important morbidity. PG was first assumed to be infectious, but is now considered an inflammatory neutrophilic disease, often associated with autoimmunity, and with chronic inflammatory and neoplastic diseases. Currently, many aspects of the underlying pathophysiology are not well understood, and etiology still remains unknown. PG presents as painful, single or multiple lesions, with several clinical variants, in different locations, with a non specific histology, which makes the diagnosis challenging and often delayed. In the classic ulcerative variant, characterized by ulcers with inflammatory undermined borders, a broad differential diagnosis of malignancy, infection, and vasculitis needs to be considered, making PG a diagnosis of exclusion. Moreover, there are no definitively accepted diagnostic criteria. Treatment is also challenging since, due to its rarity, clinical trials are difficult to perform, and consequently, there is no "gold standard" therapy. Patients frequently require aggressive immunosuppression, often in multidrug regimens that are not standardized. We reviewed the clinical challenges of PG in order to find helpful clues to improve diagnostic accuracy and the treatment options, namely topical care, systemic drugs, and the new emerging therapies that may reduce morbidity.

Objective: We conducted a retrospective study evaluating the results of photopatch tests (PPTs) performed with an extended series with the objective of determining the main photoallergens in our region and whether they would be detected by a recently recommended baseline PPT series.Materials and methods: 83 patients (58 females/25 males, mean age 54.8 years) were tested with a photoallergen series, and among these, 30 were also tested with a non-steroidal anti-inflammatory drug (NSAID) series, irradiated at D2 with 5 J/cm 2 ultraviolet A (UVA).Results: Thirty-six of 83 patients (43.3%) had at least one positive reaction, with 21 (25.3%) reacting in the photoallergen series. The main relevant reactions were as follows: 10 to ultraviolet filters (benzophenone-3 and benzophenone-4, 3 patients each), 7 to promethazine, and 2 to chlorpromazine. Twenty of 30 patients tested (70%) had a relevant positive PPT to an NSAID, 9 to piroxicam because of systemic photosensitivity, 8 to benzydamine from a topical gel or oral solution, and 2 to ketoprofen. Conclusions:Our results are discordant with most recently published studies because of the particularities of the population studied and to regional prescribing habits. Therefore, apart from the recommended baseline series of photoallergens, other substances must be tested according to regional peculiarities.