Basement membrane thickness helps to differentiate hypopigmented mycosis fungoides from clinical and pathological mimickers.

BACKGROUND: Hypopigmented mycosis fungoides (HMF) is a relatively rare subtype of mycosis fungoides (MF). The diagnosis of HMF can be quite challenging in case of insufficient diagnostic criteria due to the diverse conditions that present with hypopigmented lesions. This study aimed to evaluate the usefulness of the assessment of the basement membrane thickness (BMT) in the diagnosis of HMF. METHODS: A retrospective study was conducted on biopsy specimens of 21 HMF and 25 non-HMF cases who presented with hypopigmented lesions. The thickness of the basement membrane was evaluated in periodic acid-Schiff (PAS)-stained sections. RESULTS: The mean BMT was significantly higher in the HMF group than in the non-HMF group (P < 0.001). The best cut-off value of mean BMT for the detection of HMF verified in ROC analysis was 32.7 µm (P < 0.001) with a sensitivity of 85.7% and a specificity of 96%. CONCLUSION: Evaluation of BMT can be a useful tool to distinguish HMF from other causes of hypopigmented lesions in doubtful cases. We suggest the use of " BMT more than 33 µm" as a histopathologic criterion of HMF.

Dermatopathology practice in the era of COVID-19.

Coronavirus disease 2019 (COVID-19) pandemic has affected almost all aspects of our life including health care services. A lot of dermatopathology laboratories have stopped working during this pandemic. This article aims at reviewing the challenges and effects of COVID-19 on the practice of dermatopathology in view of the current guidelines.

Crystalglobulinemia: A Rare Presenting Manifestation of Multiple Myeloma.

ABSTRACT: Crystalglobulinemia (CG) is a rare disorder characterized by crystallization of monoclonal immunoglobulins in the microcirculation leading to multiorgan vascular thrombosis and ischemic injury. The main cause of CG is multiple myeloma. We report a case of a 52-year-old man who presented with widespread necrotizing plaques and ulcerations. A skin biopsy revealed eosinophilic rectangular-shaped crystals occluding the lumina of blood vessels with no associated features of vasculitis. The crystals were Periodic acid-Schiff stain positive. The findings were diagnostic of CG. Extensive work up lead to the discovery of multiple myeloma. Awareness of CG is important because it may be the first presenting manifestation of an underlying serious hematological malignancy.

Widespread Necrotizing Purpura and Lucio Phenomenon as the First Diagnostic Presentation of Diffuse Nonnodular Lepromatous Leprosy.

Lucio phenomenon, or Lucio leprosy, is a rare severe lepra reaction that develops exclusively in patients with diffuse nonnodular lepromatous leprosy. It is characterized by irregular, angulated, or stellar necrotizing purpuric lesions that develop ulcerations. It mainly involves the extremities and develops as a result of massive invasion of vascular endothelial cells with lepra bacilli and secondary thrombotic vascular occlusion. Antiphospholipid antibodies often are detected in cases of Lucio phenomenon, and they are thought to play a role in its pathogenesis. We report a case of diffuse lepromatous leprosy in Egypt in which Lucio phenomenon with scrotal involvement and positive antiphospholipid antibodies was the first diagnostic presentation. The patient showed an excellent response to a combination of antileprotic treatment, low dose of prednisolone, acetylsalicylic acid, and anticoagulants. In addition, surgical debridement and vacuum therapy were performed for the scrotal lesion. Awareness of this grave presentation of leprosy is important for both dermatologists and rheumatologists to avoid misdiagnosis as vasculitis/collagen disease.

Congenital trichofolliculoma: a very rare presentation.

Trichofolliculoma is an uncommon hair follicle hamartoma. It usually appears during adulthood on the face or scalp as a single, asymptomatic, skin-colored papule/nodule with small protruding hairs. Histopathological features are diagnostic. Very rare congenital cases have been reported. Herein, we report a congenital trichofolliculoma in a 15-year-old girl.

Enoxaparin induced eruptive angiokeratoma, an extremely rare side effect.

Enoxaparin is one of the most commonly used anticoagulants in the management of thromboembolic events. Herein we report a unique case of enoxaparin induced eruptive angiokeratomas in a patient with a history of ischemic cardiomyopathy who presented with acute decompensated heart failure and a new-onset generalized skin rash that bleeds on trauma, suggestive of angiokeratomas. Dermoscopic examination, as well as skin biopsy, were done upon clinical suspicion of eruptive angiokeratomas, to confirm the diagnosis. Dermoscopy showed dark lacunae surrounded by erythema, while skin biopsy revealed dilated congested capillaries lined by flat endothelial cells in the papillary dermis, both confirming the diagnosis of angiokeratoma. Enoxaparin induced eruptive angiokeratomas was suspected when the skin eruption showed spontaneous dramatic resolution upon withdrawal of enoxaparin followed by its substitution with warfarin, during the course of the patient's treatment. Enoxaparin induced eruptive angiokeratoma is an extremely rare side effect. Physicians should have a high index of clinical suspicion, and promptly discontinue the drug, as this is the only proven treatment for this condition.

Hypopigmented Interface T-Cell Dyscrasia and Hypopigmented Mycosis Fungoides: A Comparative Study.

Hypopigmented interface T-cell dyscrasia (HITCD) is a distinct form of lymphoid dyscrasia that may progress to hypopigmented mycosis fungoides (HMF). We compared both diseases as regards their CD4/CD8 phenotype and expression of granzyme B and tumor necrosis factor-alpha (TNF-α) and how these are affected by narrow-band UVB (nb-UVB). The study included 11 patients with HITCD and 9 patients with HMF. They received nb-UVB thrice weekly until complete repigmentation or a maximum of 48 sessions. Pretreatment and posttreatment biopsies were stained using anti CD4, CD8, TNF-α, and granzyme B monoclonal antibodies. Epidermal lymphocytes were CD8 predominant in 54.5% and 66.7% of HITCD and HMF cases, respectively, whereas dermal lymphocytes were CD4 predominant in 63.6% and 66.7%, respectively. Significantly, more dermal infiltrate was encountered in HMF (P = 0.041). In both diseases, granzyme B was only expressed in the dermis, whereas TNF-α was expressed both in the epidermis and dermis. No difference existed as regards the number of sessions needed to achieve repigmentation or cumulative nb-UVB dose reached at end of study. (P > 0.05). Narrow-band UVB significantly reduced only the epidermal lymphocytes in both diseases (P ≤ 0.05) with their complete disappearance in 8 (72.7%) HITCD and 6 (66.7%) HMF cases. In both diseases, nb-UVB did not affect granzyme B or TNF-α expression (P > 0.05). In conclusion, both diseases share the same phenotype, with HITCD being a milder form of T-cell dysfunction. In both diseases, epidermal lymphocytes are mainly CD8-exhausted cells lacking cytotoxicity, whereas dermal cells are mostly reactive cells exerting antitumor cytotoxicity. Tumor necrosis factor-alpha mediates hypopigmentation in both diseases and prevents disease progression. Repigmentation after nb-UVB in both diseases occurs before and independently from disappearance of the dermal infiltrate.

Apocytolysis, a proposed mechanism of blister formation in epidermolysis bullosa simplex.

Epidermolysis bullosa simplex (EBS) is caused by keratin 5 and 14 mutations. In vitro studies revealed that susceptibility to caspase 8-mediated apoptosis is increased in keratin 14 mutated keratinocytes. We aimed to investigate the role of apoptotic/inflammatory pathways in the pathogenesis of EBS by studying the expression of caspase 8 in lesional and non-lesional skin compared to controls. Ten EBS patients proved by electron microscopy and five age and sex matched healthy volunteers were the subjects of this case control study. Caspase 8 expression was studied by immunohistochemistry. Caspase 8 expression in lesional and non-lesional skin was significantly higher than in controls (p < 0.01 and p = 0.013, respectively) with no significant difference between lesional and non-lesional skin. Lesional skin had significantly higher density of dermal infiltrate (p = 0.02). Caspase 8 expression in lesional skin was significantly correlated with the extent of the disease, rate of blistering, and density of dermal infiltrate (r = 0.835; p = 0.003, r = 0.889; p = 0.001 and r = 0.776; p = 0.008 respectively). Caspase 8-mediated apoptosis is an integral component of an orchestra of events conducted by keratin mutation. Apo-cytolysis is proposed to better describe the mechanism of blistering in EBS. The small number of cases is a limitation.