Follicular keratosis of the chin is a rare and poorly understood pediatric disorder with a characteristic presentation of multiple follicular papules on the chin. Although prolonged friction or pressure over the chin is considered an etiology, such history is not present in most cases. It sometimes occurs within families without any evidence of physical trauma, suggesting a genetic predisposition of the patients to develop the disease. In the present study, we report two brothers with the disease, in whom no definite physical trauma was identified but comedo formation was evident. The clinical presentation of follicular keratosis of the chin is unique, particularly owing to its specific location on the chin with an age predilection from late childhood to puberty. We assume that the hormone status is an etiology of the disease since the chin is an area where androgenic hormones target at puberty and comedogenesis is a well-known biological function of the hormone. We also assumed that the susceptibility to the hormone may involve in the development of the familial follicular keratosis of the chin.

Cutibacterium acnes (also known as Propionibacterium acnes) has long been implicated in the pathogenesis of acne, inspiring both therapeutic and personal care approaches aiming to control the disease by controlling the bacterium. The purported association has made people with acne feel dirty and led to the-at times excessive-use of cleansers, antiseptics and antibiotics for the condition. However, recent evidence seems to weaken the case for C. acnes\' involvement. New genetics and molecular biology findings strongly suggest that abnormal differentiation of sebaceous progenitor cells causes comedones, the primary lesions in acne. Comodegenesis is initiated by androgens and is unlikely to be triggered by C. acnes, which probably doesn\'t affect sebaceous differentiation. Is there still a place for it in this understanding of acne? It is necessary to critically address this question because it has consequences for treatment. Antibiotic use for acne noticeably contributes to microbial drug resistance, which we can ill afford. In this Viewpoint, we explore if and how C. acnes (still) fits into the developing view on acne. We also briefly discuss the implications for therapy in the light of antibiotic resistance and the need for more targeted therapies.

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BACKGROUND: Milia are small, hard, white superficial epidermal cysts measuring a few millimetres that can occur during skin healing due to occlusion of pilosebaceous units. Milia rarely occur on tattoos. However, cases of allergic reactions with hyperkeratosis and open comedones have been described in the literature, sometimes under the term \"epidermal cysts\".
METHODS: We saw three patients who developed milia, including a 32-year-old man with eruptive milia 10 weeks after getting a black, red and green tattoo on his upper arm. Topical tretinoin was applied. We encountered two further cases of eruptive milia on black/grey tattoos. A fourth patient presented a massive hyperkeratotic reaction with retention comedones on the red/pink area of a tattoo.
CONCLUSIONS: The occurrence of milia and acneiform allergic reactions after tattooing is rare. We collated a total of 13 cases from the literature, of which 8 involved milia. This condition occurred within 3 months following tattooing, with no particular correlation with any given colour, and generally without any allergic reaction (except in one case). Reactions comprising excessive acneiform hyperkeratosis and open comedones were noted with pink and red inks and were a complication in a setting of allergic inflammatory reaction. However, the histopathology of these reactions is poorly described in the literature. It seems inappropriate to diagnose the condition as \"epidermal cysts\" since the lesions are not in fact simple cysts but rather retention lesions occurring during an inflammatory reaction and are thus different from post-traumatic milia.

Acne is an inflammatory disease of the pilosebaceous unit, which can be investigated in vivo using reflectance confocal microscopy (RCM) and optical coherence tomography (OCT).
By means of RCM and OCT to identify morphological characteristics of acne that may be associated with clinical acne severity.
Patients with mild to moderate facial acne (n = 14, Investigators Global Assessment scale, IGA 1-3), and healthy participants (n = 7, IGA 0) were included in this explorative study. A total of 108 RCM image blocks and 54 OCT scans (each RCM and OCT image measuring 6 × 6 mm) were captured from lesional-, perilesional, and lesion-free skin areas. Acne lesions, infundibular regions of follicles and inflammation degree were compared in acne patients and healthy participants.
Combined use of RCM and OCT demonstrated infundibular morphology, acne lesions, and blood flow. RCM images of perilesional- and lesion-free skin in acne patients revealed follicle infundibula with hyperkeratinized borders and abundant keratin plugs, contrasting skin of healthy participants. Higher acne severity related to increased number of follicles with hyperkeratotic borders (P = 0.04) and keratin plugs (P = 0.006), increased infundibulum diameter (P < 0.001), increased density of inflammatory cells (P < 0.001), and blood flow (P = 0.03). Acne lesion morphology was not associated with acne severity.
Combined use of RCM and OCT elucidated distinctive follicle infundibulum characteristics and inflammation degree that were associated with acne severity. Future trials may apply imaging techniques to support clinical acne grading, and monitor treatment efficacy. Lasers Surg. Med. 51:104-113, 2019. © 2018 Wiley Periodicals, Inc.

A 61-year-old woman with a histologically proven invasive lobular carcinoma entered a clinical trial, which involved repeat magnetic resonance imaging (MRI). The protocol of the repeated MRI described a T4 breast cancer with involvement of the skin (Fig 1). There were only 17 days between the first and second MRI and during this short time it appeared that there had been rapid disease progression. On the initial MRI, a skin comedo could be seen in the left breast close to the tumour. The patient had squeezed the skin comedo, which had become infected. The second MRI captured the infected skin comedo, which had the appearance of an extensive breast cancer with skin involvement. The patient could be mismanaged if the clinician does not correlate the clinical findings with the radiological findings.

BACKGROUND: Acne vulgaris is the most common skin disease worldwide; yet, current treatment options, although effective, are associated with unwanted side effects, chronicity, relapses and recurrences. The adequate control of the four pathogenic mechanisms, involved in the appearance of acne lesions, is paramount to treatment success.
METHODS: The authors discuss and evaluate the pathogenic pathways related to the mechanisms of action of novel molecules, which are currently under investigation for the treatment of acne vulgaris. The manuscript is based on comprehensive searches made through PubMed, GoogleScholar and ClinicalTrial.gov, using different combination of key words, which include acne vulgaris, pathogenesis, treatment, sebogenesis and Propionibacterium acnes.
CONCLUSIONS: In the near future, more effective treatments with fewer side effects are expected. The use of topical antiandrogens, acetylcholine inhibitors and PPAR modulators seem to be promising options for controlling sebum production. Retinoic acid metabolism-blocking agents and IL-1α inhibitors have the potential to become legitimate alternative options to retinoid therapy in the management of infundibular dyskeratosis. Indeed, the authors believe that there will likely be a decline in the use of antibiotics for controlling P. acnes colonization and targeting the inflammation cascade.