[Anatomoclinical and dermatoscopic study of trichoadenoma]. / Trichoadénome : description anatomoclinique et dermatoscopique.

INTRODUCTION: Trichoadenoma is a very rare follicular tumour with a remarkable histopathological appearance. In this article we present a series of 12 cases of trichoadenoma, as well as the anatomoclinical and dermatoscopic findings in a typical case. We discuss these findings in the light of an extensive literature research. PATIENTS AND METHODS: We collated 12 cases of trichoadenoma of indisputable diagnosis made at the dermatopathology laboratory of the Dermatological Clinic of the University Hospitals of Strasbourg over a 30-year period (1989-2018). RESULTS: The 12 cases comprised 7 women and 5 men, of average age 58.9 years, the majority having lesions on the cephalic extremity followed by the buttocks and thighs. Histopathological examination, which was similar in all 12 cases, showed multiple epidermal cysts containing an eosinophil lamellar keratin with a stratified wall without any visible hair, located in the superficial and mid dermis and appearing to be stacked on top of one another. In immunohistochemistry, broad spectrum keratin markers were still positive, the follicular marker Ber-EP4 weakly expressed and PHLDA1 was negative. For the case examined using polarized-light dermatoscopy, small rounded white-yellow areas were observed corresponding to cystic structures surrounded by irregular linear vessels. DISCUSSION: Trichoadenoma is a rare tumour seen in middle-aged adults of mean age 45 years, and has no sexual predominance. It is asymptomatic, slow-growing, variable in colour, measures less than one centimeter and is most often located on the face or buttocks. In terms of histology, the juxtaposition of multiple small cystic structures suggests a follicular origin. Differential diagnosis is made with trichoblastomas, which always intensely express PHLDA1 and/or Ber-EP4, desmoplastic trichoepithelioma, which consists of multiple much thinner spans in a highly fibrous stroma with clearly visible arborescent vessels over a white-yellow ivory background at dermatoscopy, microcystic carcinoma, which has a deeper extension, and plaque milium, in which the cysts are larger.

[Dermatofibroma with sebaceous induction]. / Histiocytofibrome avec induction sébacée.

BACKGROUND: Histiocytoma or dermatofibroma (DF) is a common benign skin tumour with several clinical and histopathological variants. Sebaceous induction overlying a dermatofibroma is rare and infrequently reported. Using a detailed clinical case, herein the semiological and dermoscopic features of this lesion are described and illustrated, and the differential diagnoses presented. PATIENTS AND METHODS: A 52-year-old man consulted for a physical examination, which revealed a firm papular lesion of the upper middle back. The upper part of the nodule was covered by a slightly hyperpigmented surface, with numerous small whitish lobules. Microscopic examination revealed a dermatofibroma with sebaceous induction. DISCUSSION: Sebaceous induction overlying a dermatofibroma is not frequent, and it occurs in most cases on or near the shoulder. The typical dermoscopic pattern involves many whitish globules or clumps grouped into clusters. The aetiology is unknown but could stem from a conducive microenvironment in shoulder skin, associated with growth factors secreted by the DF.

[Paget's disease of ectopic breast]. / Maladie de Paget sur sein surnuméraire.

BACKGROUND: Paget's disease of the breast is rare, even more so when it occurs in a supernumerary breast since diagnosis is delayed due to lack of exploration and ignorance of the pathology of ectopic breast. Based on an original clinical case, we provide a clinical update concerning ectopic breast and ectopic carcinoma, including Paget's disease. PATIENTS AND METHODS: A 44-year-old woman had complained of pain in the area of her supernumerary breast for several months. The ultrasound examination was normal but the unexplained symptoms led to performance of an excision biopsy of the lesion. This showed strictly intra-epidermal Paget's disease measuring 2mm, without any underlying carcinoma. A wider excision was performed. Follow-up at one year showed no recurrence. DISCUSSION: An ectopic breast, present in 6 % of the population, is often ignored, despite being subject to the same diseases as anatomical breasts: it is at the origin of 0.6 % of breast cancers. Paget's disease is a rare in situ adenocarcinoma comprising fewer than 3 % of cases of breast cancer. It is extremely rare in ectopic breast. Ours is only the fourth reported case in the literature. This case is original because of the lack of objective clinical signs. Subjective symptoms such as pain, tingling, burning sensation and pruritus related to the supernumerary breast must be taken into consideration in order to enable early diagnosis of Paget's disease. Exploration by ultrasound and mammography generally appears flawed. Breast MRI may be useful but is not performed routinely. A promising future approach may consist of confocal microscopy screening of all ectopic breasts with areola or nipple patches, since this method enables the visualization of Paget cells and their organization.

[Nested melanoma]. / Mélanome en thèques.

BACKGROUND: Nested melanoma in elderly subjects is an entity that has been reported in the literature only since 2012. In this paper, we describe its distinctive clinical, dermatoscopic and histopathological features and compare them to previous published cases, with the aim of highlighting certain specific criteria of this melanoma subtype. CASE REPORT: A 52-year-old man was referred for the presence on his chest of a large suspicious pigmented lesion of irregular shape and colour. Dermatoscopically, the lesion was chaotic and characterized by a black, structureless, eccentric area with some peripheral globules as well as some segmental radial lines. Histopathological examination revealed the presence of an asymmetric lesion with large junctional melanocytic nests showing a focal tendency to gathering and some cytological atypia. A diagnosis of nested melanoma was ultimately made. DISCUSSION: Nested melanoma of the elderly represents a distinct anatomoclinical variant of superficial spreading melanoma. Clinically, the lesion is usually large and occurs in photodamaged skin. We would stress that the "elderly" criterion is not mandatory given the numerous cases reported in people under 60 years. The main dermatoscopic feature is a globular pattern, but several features characteristic of superficial spreading melanoma may also be present. Histological diagnosis may be difficult because of the mainly nested pattern, and the condition may be confused histologically with a benign junctional nevus. But these large junctional nests of different sizes, with bridging and cytonuclear atypias, together with asymmetry of the lesions are the hallmark of this special kind of melanoma.