Clinical and genetic features of Chinese patients with lichen and macular primary localized cutaneous amyloidosis

Primary Localized Cutaneous Amyloidosis in Central Europe: A Retrospective Monocentric Study on Epidemiology and Therapy

Amyloid deposits can be the cause of many chronic diseases. Primary localized cutaneous amyloidosis (PLCA) is a chronic dermatologic condition with amyloid deposits in the papillary dermis. The most common types of the keratinocyte-derived form of PLCA include macular (MA), lichen (LA), and biphasic (BA) amyloidosis. The estimated prevalence of PLCA in the Asian population is 0.98/10,000, which is higher than in the European population; thus, epidemiologic data on PLCA in the Caucasian population are limited. We performed a retrospective single-center study analyzing epidemiologic characteristics of a Central European PLCA population. Epidemiologic data regarding age, sex, skin phototype (Fitzpatrick scale I-VI), disease duration, comorbidities, history of atopy, and family history of PLCA were collected. Clinical characteristics, localization of PLCA lesions, applied therapies and treatment outcomes were also analyzed. Dermoscopic characteristics were also evaluated. A total of 41 patients diagnosed with PLCA were included, with 22 presenting with macular, 18 with lichen, and 1 with biphasic amyloidosis. The male/female ratio was 16/25, and mean age at diagnosis was 54.6 ± 15.2 years (range 27-87 years). The mean age at the onset of PLCA was 53 ± 16.1 years (range 19-79 years) in MA, 46.7 ± 18.2 years (range 14-73 years) in LA, and 26 years in BA. The interscapular region in MA and the extensor surface of the lower extremities in LA proved to be localization-related areas. In our center, a wide range of therapeutic options was applied, with the most prescribed being topical corticosteroids in all types of PLCA. We presented a retrospective, monocentric study on the epidemiology of PLCA in the Central European region. By examining the medical data of a significant number of PLCA patients, we compared our epidemiologic data with that of the Asian PLCA population. Due to the rarity of the condition, further randomized controlled trials and guidelines are needed to improve therapeutic outcomes.

Characterization of Epidermal Function in Individuals with Primary Cutaneous Amyloidosis

Purpose

To compare epidermal biophysical properties, indicators of epidermal function, in individuals with and without primary cutaneous amyloidosis (PCA).

Patients and Methods

This study incorporated 189 patients with PCA and 166 healthy individuals. The GPSkin Barrier was employed to measure transepidermal water loss (TEWL) rates and hydration levels of the stratum corneum. The Sebumeter and the Skin pH Meter were utilized to determine the skin surface's sebum content and pH, respectively. The severity of pruritus in participants was evaluated using the visual analog scale (VAS).

Results

Compared to the control group without PCA, individuals with PCA displayed a notable increase in skin surface pH and TEWL and a decrease in the hydration levels of the stratum corneum (p<0.0001 for all parameters). Additionally, the sebum content was markedly lower in those with PCA than in the controls (p<0.0001). Of particular note, both TEWL and skin surface pH at the lesion sites on the back and the shin were more elevated in lichenoid amyloidosis (LA) and in macular amyloidosis (MA), whereas hydration levels of the stratum corneum and sebum levels were diminished in LA compared to MA (p<0.05). In conclusion, both hydration levels of the stratum corneum and sebum content exhibited an inverse relationship with pruritus severity, whereas TEWL and skin surface pH demonstrated a positive correlation with pruritus intensity.

Conclusion

The function of the epidermis is compromised in individuals diagnosed with PCA. However, the mechanisms underlying these changes await further investigation.

Barrier function and ultrastructure characteristics of epidermis in patients with primary cutaneous amyloidosis

Previous studies on primary cutaneous amyloidosis (PCA) have mainly focused on exploring genetic mutation and components of amyloid in patients with PCA. However, studies on skin barrier function in PCA patients are scarce. Here, we detected the skin barrier function in PCA patients and healthy people by using noninvasive techniques and characterized ultrastructural features of PCA lesions compared with healthy people using transmission electron microscopy (TEM). The expression of proteins related to skin barrier function was examined by immunohistochemistry staining. A total of 191 patients with clinically diagnosed PCA and 168 healthy individuals were enrolled in the study. Our analysis revealed that all investigated lesion areas displayed higher transepidermal water loss and pH values, and lower Sebum levels and stratum corneum hydration levels in PCA patients compared with the same site area in healthy individuals. The TEM results showed that the intercellular spaces between the basal cells were enlarged and the number of hemidesmosomes decreased in PCA lesions. Immunohistochemical staining showed that the expression of integrin α6 and E-cadherin in PCA patients was less than that in healthy controls, while no differences in the expression of loricrin and filaggrin were observed. Our study revealed that individuals with PCA displayed skin barrier dysfunction, which may be related to alterations in epidermal ultrastructure and a decrease in the skin barrier-related protein E-cadherin. However, the molecular mechanisms underlying skin barrier dysfunction in PCA remain to be elucidated.

AHNAK, regulated by the OSM/OSMR signaling, involved in the development of primary localized cutaneous amyloidosis

BACKGROUND

Primary localized cutaneous amyloidosis (PLCA) is a chronic skin disease characterized by aberrant keratinocyte differentiation, epidermal hyperproliferation, and amyloid deposits. Previously, we demonstrated OSMR loss-function mutants enhanced basal keratinocyte differentiation through the OSMR/STAT5/KLF7 signaling in PLCA patients.

OBJECTIVE

To investigate the underlying mechanisms involved in basal keratinocyte proliferation in PLCA patients that remain unclear.

METHODS

Patients with pathologically confirmed PLCA visiting the dermatologic outpatient clinic were involved in the study. Laser capture microdissection and mass spectrometry analysis, gene-edited mice, 3D human epidermis culture, flow cytometry, western blot, qRT-PCR and RNA sequencing were used to explore the underlying molecular mechanisms.

RESULTS

In this study, we found that AHNAK peptide fragments were enriched in the lesions of PLCA patients, as detected by laser capture microdissection and mass spectrometry analysis. The upregulated expression of AHNAK was further confirmed using immunohistochemical staining. qRT-PCR and flow cytometry revealed that pre-treatment with OSM can inhibit AHNAK expression in HaCaT cells, NHEKs, and 3D human skin models, but OSMR knockout or OSMR mutations abolished this down-regulation trend. Similar results were obtained in wild-type and OSMR knockout mice. More importantly, EdU incorporation and FACS assays demonstrated the knockdown of AHNAK could induce G1 phase cell cycle arrest and inhibit keratinocyte proliferation. Furthermore, RNA sequencing revealed that AHNAK knockdown regulated keratinocyte differentiation.

CONCLUSION

Taken together, these data indicated that the elevated expression of AHNAK by OSMR mutations led to hyperproliferation and overdifferentiation of keratinocytes, and the discovered mechanism might provide insights into potential therapeutic targets for PLCA.

Coexistent Lichen Amyloidosis and Acquired Reactive Perforating Collagenosis in Type 2 Diabetes Mellitus and Post-Thyroidectomy Hypothyroidism Due to Papillary Thyroid Carcinoma: A Rare Case

An abundance of endocrine receptors is expressed on the skin and becomes the target of many hormones. This was associated with various skin diseases that might occur in some endocrine diseases eg, lichen amyloidosis (LA) and acquired reactive perforating collagenosis (ARPC). Here, we report a coexistent LA and ARPC in a 55-year-old woman, characterized with multiple pruritic hyperkeratotic papules and plaques on both arms accompanied by pruritic hyperkeratotic papules and nodules on both legs. She had a history of type 2 diabetes mellitus (DM) and post-thyroidectomy hypothyroidism due to papillary thyroid carcinoma. Histopathological examination revealed amyloid deposition in the papillary dermis corresponding with LA and cup-shaped epidermal depression filled with collagen corresponding with ARPC. The hyperkeratotic papules and nodules flattened in one month after application of 0.05% clobetasol propionate ointment with occlusion on both arms and 0.05% retinoic acid gel on both legs. Hyperkeratotic papules, nodules, and plaques in a patient with a history of endocrine diseases, such as type 2 DM and thyroid disorders should undergo histopathological examination to confirm the diagnosis of skin diseases eg, LA or ARPC.

Friction-Aggravated Skin Disorders-A Review of Mechanism and Related Diseases

ABSTRACT

Skin is subject to frequent friction injury. Friction affects different structures of the skin, including keratinocytes, melanocytes, fibroblasts, and follicular units. Friction can also stimulate cytokine production. Friction is sensed by the mechanoreceptors, resulting in signal transduction to the nucleus, activating transcription factors and mechanoresponsive genes. Numerous friction-aggravated diseases have been identified, including inflammatory, depositional, follicular, genetic, infectious, and vesiculobullous disorders. Friction, as a potential modifiable aggravator, should be considered when skin diseases are located at friction-prone areas.

Primary Localized Cutaneous Amyloidosis of Keratinocyte Origin: An Update with Emphasis on Atypical Clinical Variants

Amyloid is a protein derived from at least 20 different substances. Once misfolded, it results in a group of cutaneous and systemic conditions. Primary localized cutaneous amyloidosis of keratinocyte origin is a very common subtype that can manifest either as lichen or macular amyloidosis, lacking systemic involvement. Lichen amyloidosis often presents as multiple hyperpigmented papules on the lower extremities whereas macular amyloidosis is classically characterized by dark brown rippled macules on the interscapular area. Review of the literature reveals that in addition to the classical presentation of primary localized cutaneous amyloidosis there exists a plethora of various manifestations that can be grouped into either geographic or morphologic categories. This review provides clinicians with the intimate knowledge of these presentations and summarizes the available treatment modalities.

Diagnosis of Primary Cutaneous Amyloidosis by Rapid 4,6-Diamidino-2-Phenylindole Staining

BACKGROUND

Quick and accurate diagnosis of primary cutaneous amyloidosis (PCA) may be difficult because its symptoms are often subtle and nonspecific.

OBJECTIVE

We sought to review the literature on the roles of various staining methods in the diagnosis of amyloidosis and demonstrate added benefits of using rapid 4,6-diamidino-2-phenylindole (DAPI) staining in the diagnosis of PCA.

METHODS

Three groups of cases, namely, PCA, neurodermatitis, and prurigo nodularis, were retrieved from a computerized pathology database for study, and their paraffin-embedded tissue blocks were cut following standard procedures. The tissue sections were stained with three stains: hematoxylin-eosin (HE), Congo red, and DAPI stains, and examined under the microscope to compare the staining patterns of these three methods. We also performed amyloid keratin and apolipoprotein E (APOE) staining on the sections of PCA in order to further support our conclusion. The PCA sections were read by junior and senior dermatopathologists for comparison.

RESULTS

The sensitivity of DAPI staining for PCA was significantly higher than that of Congo red staining and HE staining (p < 0.001). This statement holds true whether the experiment was grouped in one sample or was divided into groups of junior and senior dermatopathologists (p < 0.001). The DAPI-positive staining areas, except for the nuclei, were consistent with the amyloid deposition areas. In this study, DAPI staining had a sensitivity of 98.6% and a specificity of 100%.

CONCLUSION

DAPI staining could serve as a useful technique to establish the diagnosis of PCA, and its high efficacy in diagnosing PCA makes it less dependent on the experience levels of the evaluators. Additionally, the binding of DAPI to the A-T-rich sequence of double-stranded DNA suggests that amyloid may contain DNA or a similarly structured nucleic acid.