MLNR is an independent predictor of PTC recurrence and enhances the predictive value of TNM nodal classification.

<b><i>Background:</i></b> Primary cutaneous CD4+ small/medium pleomorphic T-cell lymphoproliferative disorder (SMPLPD) is a provisional entity within the 2016 World Health Organization classification of primary cutaneous lymphomas. The condition is currently classified as a lymphoproliferative disorder to emphasize its benign course and discourage aggressive, systemic treatment modalities. <b><i>Objective:</i></b> To provide a relevant synthesis for the dermatological practitioner on the prevalence, presentation, and treatment of SMPLPD. <b><i>Methods:</i></b> We conducted an updated systematic literature review and a retrospective chart review of diagnosed cases of SMPLPD from 2 Canadian academic cutaneous lymphoma centers. <b><i>Results:</i></b> A total of 23 studies with 136 cases were extracted from the systematic review and 24 patients from our retrospective chart review. SMPLPD proved relatively common accounting for 12.5% of all cutaneous T-cell lymphomas encountered in our cutaneous lymphoma clinics, second in frequency only to mycosis fungoides. The typical clinical presentation was that of an older individual (median age 59 years) with an asymptomatic solitary lesion on their upper extremity. The most common clinical differentials were cutaneous lymphoid hyperplasia, basal cell carcinoma, and lymphoma unspecified. T follicular helper markers were reliably detected. The main treatment modalities were surgical excision, local radiation therapy, and topical or intralesional steroids. Cure was achieved in the vast majority of cases. <b><i>Conclusions:</i></b> SMPLPD is an underdiagnosed T-cell lymphoma with an overtly benign clinical course. The condition has an excellent prognosis and responds well to skin-directed therapies. Practitioners should be aware of this condition to avoid aggressive systemic treatments.

Background Filaggrin is a protein integral to the structure and function of the epidermis. Filaggrin (FLG) loss‐of‐function (LOF) mutations are common and increase the risk of developing atopic dermatitis (AD) and ichthyosis vulgaris (IV). Epidemiologic data suggest a link between skin cancer and AD. We examined if FLG staining pattern can be used to characterize cutaneous squamous cell carcinomas (SCC), basal cell carcinomas (BCC), and reactive squamous epithelium. Methods Tissue microarrays (TMAs) were created from 196 cases of formalin‐fixed paraffin‐embedded (FFPE) SCC and 144 BCC cases. TMAs and sections of reactive squamous epithelium were stained with optimized anti‐FLG antibody and evaluated for FLG expression (normal, abnormal, or negative). Results FLG was absent in poorly differentiated (PD) compared to well‐differentiated (WD) SCC (P < .0001) and moderately‐differentiated (MD) (P = .0231) SCC, and in MD compared to WD SCC (P = .0099). Abnormal staining was significantly increased in PD compared to WD cases (P = .0039) and in MD compared to WD cases (P = .0006). Most BCC did not exhibit FLG expression (P < .05). Reactive squamous epithelium demonstrated normal, but exaggerated FLG expression. Conclusions Our findings demonstrate the differences in FLG expression patterns in types of keratinocyte carcinomas and their mimickers.

Dermatology has a very distinctive lexicon. The term pityriasis refers to several dermatologic conditions which all feature scaling of the skin. According to the Merriam‐Webster dictionary, the term pityriasis was first used in print in 1684. Although the diseases beginning with the name pityriasis are of diverse causation, they do represent important dermatologic diseases, with some common and others quite rare. It is important for dermatologists to be aware and updated on all pityriasis conditions in dermatology.

Fosfomycin is an antibiotic often used to treat urinary tract infections (UTIs) with only rare transient hepatotoxicity. We present a case of fosfomycin-induced liver injury and describe the histopathologic findings on biopsy. A 64 year-old female patient with no prior liver disease or risk factors was started on fosfomycin as prophylaxis for recurrent UTIs. Within a week of her first dose she presented with fatigue, jaundice, and mixed liver enzyme elevation. Clinical workup for acute liver injury was unremarkable, and biopsy showed panacinar and portal necroinflammation with predominantly lymphocytic infiltrate and cholestasis. This was thought to be likely related to fosfomycin exposure. While liver enzymes trended down, bilirubin initially remained elevated. However, within three months the patient achieved clinical and biochemical recovery. Only two other reports of fosfomycin-induced liver injury requiring biopsy were found. Both developed acute cholestatic hepatitis within days of exposure, and subsequent biopsy similarly showed lymphocytic necroinflammation. Although one patient initially developed acute liver failure, both recovered fully within few months. Overall, these cases suggest likely an idiosyncratic or immune-mediated liver toxicity of fosfomycin which is typically self-limited with rapid recovery. Liver biopsy may be useful in confirming the diagnosis.