Amyloidogenesis in organ-limited cutaneous amyloidosis: an antigenic identity between epidermal keratin and skin amyloid

Recent Advancements in Biosensors for the Detection and Characterization of Amyloids: A Review

Modern medicine has increased the human lifespan. However, with an increase in average lifespan risk of amyloidosis increases. Amyloidosis is a condition characterized by protein misfolding and aggregation. Early detection of amyloidosis is crucial, yet conventional diagnostic methods are costly and lack precision, necessitating innovative tools. This review explores recent advancements in diverse amyloid detection methodologies, highlighting the need for interdisciplinary research to develop a miniaturized electrochemical biosensor leveraging nanotechnology. However, the diagnostics industry faces obstacles such as skilled labor shortages, standardized selection processes, and concurrent multi-analyte identification challenges. Research efforts are focused on integrating electrochemical techniques into clinical applications and diagnostics, with the successful transition of miniaturized technologies from development to testing posing a significant hurdle. Label-free transduction techniques like voltammetry and electrochemical impedance spectroscopy (EIS) have gained traction due to their rapid, cost-effective, and user-friendly nature.

Fibril structures of TFG protein mutants validate the identification of TFG as a disease-related amyloid protein by the IMPAcT method

We previously presented a bioinformatic method for identifying diseases that arise from a mutation in a protein's low-complexity domain that drives the protein into pathogenic amyloid fibrils. One protein so identified was the tropomyosin-receptor kinase-fused gene protein (TRK-fused gene protein or TFG). Mutations in TFG are associated with degenerative neurological conditions. Here, we present experimental evidence that confirms our prediction that these conditions are amyloid-related. We find that the low-complexity domain of TFG containing the disease-related mutations G269V or P285L forms amyloid fibrils, and we determine their structures using cryo-electron microscopy (cryo-EM). These structures are unmistakably amyloid in nature and confirm the propensity of the mutant TFG low-complexity domain to form amyloid fibrils. Also, despite resulting from a pathogenic mutation, the fibril structures bear some similarities to other amyloid structures that are thought to be nonpathogenic and even functional, but there are other factors that support these structures' relevance to disease, including an increased propensity to form amyloid compared with the wild-type sequence, structure-stabilizing influence from the mutant residues themselves, and double-protofilament amyloid cores. Our findings elucidate two potentially disease-relevant structures of a previously unknown amyloid and also show how the structural features of pathogenic amyloid fibrils may not conform to the features commonly associated with pathogenicity.

Successful treatment of lichen amyloidosis coexisting with atopic dermatitis by dupilumab: Four case reports

BACKGROUND

Lichen amyloidosis (LA) is a chronic, severely pruritic skin disease, which is the most common form of primary cutaneous amyloidosis. The treatment of LA has been considered to be difficult. LA may be associated with atopic dermatitis (AD), and in this setting, the treatment options may be more limited. Herein, we report four cases of LA associated with AD successfully treated by dupilumab.

CASE SUMMARY

In this article, we describe four cases of patients who presented with recurrent skin rash accompanied by severe generalized intractable pruritus, diagnosed with refractory LA coexisting with chronic AD. Previous treatments had not produced any apparent improvement. Thus, we administered dupilumab injection subcutaneously at a dose of 600 mg for the first time and 300 mg every 2 wk thereafter. Their lesions all markedly improved.

CONCLUSION

Dupilumab may be a new useful treatment for LA coexisting with AD.

Keratinic amyloid deposition in canine hair follicle tumors

Keratinic primary localized cutaneous amyloidosis is a disease in humans; however, no similar condition has been reported in animals. This study aimed to investigate cutaneous keratinic amyloid deposition in dogs and elucidate its etiology. Canine hair follicle tumor tissues were histopathologically analyzed. Immunohistochemistry and mass spectrometry-based proteomic analyses were performed to identify precursor protein candidates. Structural prediction and in vitro fibrillization analyses were conducted to determine the amyloidogenic region and gene sequencing analysis was performed to assess mutations. Of the 266 samples, 16 had amyloid deposition. Amyloid deposits were found in the stroma of tumors and in the margins of keratin debris and around normal hair follicles. Cytokeratin 5 (CK5) was identified as a precursor protein candidate. C-terminal truncation of CK5 was observed in amyloid deposits, and the truncation sites varied depending on the deposition pattern. There was a significantly higher incidence of amyloid deposition in Shiba dogs, and CK5 amino acid polymorphisms were identified in these dogs. A part of the C-terminal region of both canine and human CK5 exhibited highly amyloidogenic properties in vitro. This study revealed the existence of cutaneous keratinic amyloid deposition in animals and identified CK5 as an amyloid precursor protein, providing novel insights into understanding the etiology of cutaneous amyloidosis.

Fibulin-4 accelerates amyloid formation through binding with a keratin 5 peptide fragment

Keratins are the major amyloid fibril component in localized cutaneous amyloidosis. We analyzed the amyloid components in the skin of patients with localized cutaneous amyloidosis by immunohistochemical staining using antisera against extracellular matrix proteins and keratin 5 (K5). Fibulin-4 and K5 colocalized in the amyloid deposits. Using 14 synthetic peptides, we screened for amyloidogenic sequences in the C-terminal region of K5, including the α-helical rod domain and the tail domain. Two peptides stained with thioflavin T possessed a β-sheet structure and formed amyloid-like fibrils. Among the amyloidogenic peptides, a peptide KT5-6 (YQELMNTKLALDVEIATYRKLLEGE) derived from the α-helical rod domain of K5 specifically bound to fibulin-4. In addition, amyloid formation of KT5-6 was accelerated by fibulin-4. These results suggest that degraded fragments of K5 containing the KT5-6 sequence form amyloid fibrils with fibulin-4. The data further suggest that degraded fragments of K5 and fibulin-4 have the potential to initiate cutaneous amyloidosis.

Macular Amyloidosis and Epstein-Barr Virus

Background. Amyloidosis is extracellular precipitation of eosinophilic hyaline material of self-origin with special staining features and fibrillar ultrastructure. Macular amyloidosis is limited to the skin, and several factors have been proposed for its pathogenesis. Detection of Epstein-Barr virus (EBV) DNA in this lesion suggests that this virus can play a role in pathogenesis of this disease. Objective. EBV DNA detection was done on 30 skin samples with a diagnosis of macular amyloidosis and 31 healthy skin samples in the margin of removed melanocytic nevi by using PCR. Results. In patients positive for beta-globin gene in PCR, BLLF1 gene of EBV virus was positive in 23 patients (8 patients in case and 15 patients in the control group). There was no significant difference in presence of EBV DNA between macular amyloidosis (3.8%) and control (23.8%) groups (P = 0.08). Conclusion. The findings of this study showed that EBV is not involved in pathogenesis of macular amyloidosis.

In vitro amyloidogenic peptides of galectin-7: possible mechanism of amyloidogenesis of primary localized cutaneous amyloidosis

Pathogenesis of primary localized cutaneous amyloidosis (PLCA) is unclear, but pathogenic relationship to keratinocyte apoptosis has been implicated. We have previously identified galectin-7, actin, and cytokeratins as the major constituents of PLCA. Determination of the amyloidogenetic potential of these proteins by thioflavin T (ThT) method demonstrated that galectin-7 molecule incubated at pH 2.0 was capable of binding to the dye, but failed to form amyloid fibrils. When a series of galectin-7 fragments containing β-strand peptides were prepared to compare their amyloidogenesis, Ser(31)-Gln(67) and Arg(120)-Phe(136) were aggregated to form amyloid fibrils at pH 2.0. The rates of aggregation of Ser(31)-Gln(67) and Arg(120)-Phe(136) were dose-dependent with maximal ThT levels after 3 and 48 h, respectively. Their synthetic analogs, Phe(33)-Lys(65) and Leu(121)-Arg(134), which are both putative tryptic peptides, showed comparable amyloidogenesis. The addition of sonicated fibrous form of Ser(31)-Gln(67) or Phe(33)-Lys(65) to monomeric Ser(31)-Gln(67) or Phe(33)-Lys(65) solution, respectively, resulted in an increased rate of aggregation and extension of amyloid fibrils. Amyloidogenic potentials of Ser(31)-Gln(67) and Phe(33)-Lys(65) were inhibited by actin and cytokeratin fragments, whereas those of Arg(120)-Phe(136) and Leu(121)-Arg(134) were enhanced in the presence of Gly(84)-Arg(113), a putative tryptic peptide of galectin-7. Degraded fragments of the galectin-7 molecule produced by limited trypsin digestion, formed amyloid fibrils after incubation at pH 2.0. These results suggest that the tryptic peptides of galectin-7 released at neutral pH, may lead to amyloid fibril formation of PLCA in the intracellular acidified conditions during keratinocyte apoptosis via regulation by the galectin-7 peptide as well as actin and cytokeratins.

Localized amyloidosis of the vulva with and without vulvar intraepithelial neoplasia: report of a series

Localized primary cutaneous amyloidosis is uncommon in Europe and North America and is infrequently reported in the English literature. The constituents of such deposits have not been previously examined; this series characterizes amyloid deposits in localized vulvar amyloidosis and their association with vulvar intraepithelial neoplasia. All biopsies and excisions of vulva over 18 months were reviewed. Cases with suspected amyloidosis were retrieved after institutional review board approval. Twenty cases mimicking amyloidosis were selected as controls. All study and control cases were stained with Congo red. Four Congo red-positive study cases were studied by liquid chromatography-tandem mass spectrometry. Of 27 Congo red-positive study cases, 25 were then examined by immunohistochemical stains with antibodies to cytokeratin 5 (CK5) and cytokeratin 14 (CK14). Of 149 cases reviewed, 26 localized and 1 systemic vulvar amyloidosis were identified. Liquid chromatography-tandem mass spectrometry analysis of the deposits revealed unique peptide profile consistent with CK5 and CK14. Immunohistochemical staining with antibodies to CK5 and CK14 also detected these components in the deposits. The vulvar deposit of systemic amyloidosis consisted of amyloid light chain (λ)-type amyloid deposit. All control cases were negative for Congo red. Keratin-associated amyloid materials (CK5 and CK14) were found to be unique in localized vulvar amyloidosis. Leakage of keratins from the basal layer of the epithelium into the superficial dermis may have been the possible source of the deposits. It appears to be associated with both high-grade and low-grade vulvar intraepithelial neoplasias and, rarely, lichen sclerosus, seborrheic keratosis, and benign vulvar skin.

A clinico-epidemiological study of macular amyloidosis from north India

BACKGROUND

Macular amyloidosis (MA) is the most subtle form of cutaneous amyloidosis, characterized by brownish macules in a rippled pattern, distributed predominantly over the trunk and extremities. MA has a high incidence in Asia, Middle East, and South America. Its etiology has yet to be fully elucidated though various risk factors such as sex, race, genetic predisposition, exposure to sunlight, atopy and friction and even auto-immunity have been implicated.

AIM

This study attempts to evaluate the epidemiology and risk factors in the etiology of MA.

MATERIALS AND METHODS

Clinical history and risk factors of 50 patients with a clinical diagnosis of MA were evaluated. Skin biopsies of 26 randomly selected patients were studied for the deposition of amyloid.

RESULTS

We observed a characteristic female preponderance (88%) with a female to male ratio of 7.3:1, with a mean age of onset of MA being earlier in females. Upper back was involved in 80% of patients and sun-exposed sites were involved in 64% cases. Incidence of MA was high in patients with skin phototype III. Role of friction was inconclusive

CONCLUSION

Lack of clear-cut etiological factors makes it difficult to suggest a reasonable therapeutic modality. Histopathology is not specific and amyloid deposits can be demonstrated only in a small number of patients. For want of the requisite information on the natural course and definitive etiology, the disease MA remains an enigma and a source of concern for the suffering patients.

Cutaneous amyloidosis: a concept review

Concepts and semantics are crucial for good communication between clinicians and pathologists. Amyloidosis was described more than 150 years ago. Therefore, the terminology related to it is abundant, varied, and sometimes complex. In this report, we intend to discuss several terms related to the disease, with special emphasis on cutaneous amyloidosis. We present a review, from Virchow to present, of the concepts related to amyloidosis: its nature, the classification of cutaneous forms of the disease, and the techniques used in its diagnosis.

Association of skin with the pathogenesis and treatment of neurodegenerative amyloidosis

Amyloidosis are a large group of conformational diseases characterized by abnormal protein folding and assembly which results in the accumulation of insoluble protein aggregates that may accumulate systemically or locally in certain organs or tissue. In local amyloidosis, amyloid deposits are restricted to a particular organ or tissue. Alzheimer’s, Parkinson’s disease, and amyotrophic lateral sclerosis are some examples of neurodegenerative amyloidosis. Local manifestation of protein aggregation in the skin has also been reported. Brain and skin are highly connected at a physiological and pathological level. Recently several studies demonstrated a strong connection between brain and skin in different amyloid diseases. In the present review, we discuss the relevance of the “brain–skin connection” in different neurodegenerative amyloidosis, not only at the pathological level, but also as a strategy for the treatment of these diseases.

Oncostatin M receptor-beta mutations underlie familial primary localized cutaneous amyloidosis

Familial primary localized cutaneous amyloidosis (FPLCA) is an autosomal-dominant disorder associated with chronic skin itching and deposition of epidermal keratin filament-associated amyloid material in the dermis. FPLCA has been mapped to 5p13.1-q11.2, and by candidate gene analysis, we identified missense mutations in the OSMR gene, encoding oncostatin M-specific receptor beta (OSMRbeta), in three families. OSMRbeta is a component of the oncostatin M (OSM) type II receptor and the interleukin (IL)-31 receptor, and cultured FPLCA keratinocytes showed reduced activation of Jak/STAT, MAPK, and PI3K/Akt pathways after OSM or IL-31 cytokine stimulation. The pathogenic amino acid substitutions are located within the extracellular fibronectin type III-like (FNIII) domains, regions critical for receptor dimerization and function. OSM and IL-31 signaling have been implicated in keratinocyte cell proliferation, differentiation, apoptosis, and inflammation, but our OSMR data in individuals with FPLCA represent the first human germline mutations in this cytokine receptor complex and provide new insight into mechanisms of skin itching.

Porocarcinoma Arising in Pigmented Hidroacanthoma Simplex

Hidroacanthoma simplex (HAS) is a rare benign tumor that is also known as intraepidermal poroma. While there have been a few reports of HAS with malignant transformation (porocarcinoma), we report an unusual case of porocarcinoma, arising in a pigmented HAS, the latter also showing secondary amyloid deposits. An 80-year-old Japanese man presented with a cutaneous tumor on his left buttock, which had first been noticed in his childhood. The tumor consisted of flat pigmented plaque and a depigmented papule with erosion. Histologic analysis revealed many pigmented and well-defined nests within the epidermis of the flat pigmented portion. The nests were composed of cuboidal to oval and occasionally elongated, bland, basaloid cells with numerous melanin granules. In addition, there were infrequently ductal structures and small clusters of sebocytes, and abundant amyloid deposits in the upper dermis. These findings were consistent with pigmented HAS with amyloid deposition. In the depigmented portion, markedly atypical cells with occasional ductal structures and intracytoplasmic lumina extended throughout the entire thickness of the epidermis, with minimal invasion of the dermis. We considered this portion of the tumor to be a porocarcinoma. Since the two portions of the tumor were continuous, we made a final diagnosis of porocarcinoma arising in pre-existing pigmented HAS with amyloid deposition.

Discoid lupus erythematosus with secondary amyloidosis

BACKGROUND

Secondary localized cutaneous amyloidosis is a clinically unapparent phenomenon associated with various cutaneous pathologies, usually tumours of epidermal origin. The amyloid is thought to be derived from keratinocytes.

OBJECTIVES

To characterize the amyloid deposition observed incidentally within lesional biopsies from three patients with discoid lupus erythematosus (DLE), and retrospectively to study the phenomenon within DLE skin samples.

METHODS

Localized amyloid deposition was observed in three cases of DLE by immunofluorescence studies, and these cases were further studied by histology and immunohistochemistry using a monoclonal anticytokeratin antibody. Retrospective histological review of DLE tissue specimens archived over 12 months was performed to look for evidence of previously undetected amyloid.

RESULTS

Amyloid deposition was confirmed histologically in the three index cases by staining with Congo red and thioflavin T. Positive staining with an anticytokeratin antibody demonstrated the epidermal origin of the amyloid protein. Of the 18 archived cases reviewed amyloid was retrospectively detected in one sample.

CONCLUSIONS

Secondary cutaneous amyloidosis of keratinocyte origin can be seen in DLE lesions. It may be a not infrequent occurrence and may remain under-reported. We discuss the possible role of disease chronicity and colloid body degradation in the pathogenesis of amyloidosis.

Scleroderma and pseudoscleroderma: uncommon presentations

Scleroderma is characterized by major clinical symptoms, but a number of unrelated disease may mimic these features more or less completely. Even scleroderma itself sometimes presents in an unusual manner. This article deals with uncommon presentations of true scleroderma and its variants and pseudo -scleroderma diseases.

Cytokeratin contents of basal cell carcinoma, epidermis overlying tumour, and associated stromal amyloidosis: an immunohistochemical study

Cytokeratins (CKs) are expressed specifically in the cytoplasm of epithelial cells. We investigated the expression of CKs immunohistochemically in basal cell carcinomas (BCCs), epidermis overlying tumour, and skin tumor-associated amyloidosis (STA). Twenty cases of BCC, 11 of which had STA were included to the study. The primary antibodies of CK1-8 (AE3), CK10 (DEK-10), CK14 (LL002), CK17 (E3), CK18 (DC10), CK19 (KS19.1), CK 5/6/18 (LP34), CK8/18 (5D3) were applied to the section immunohistochemically. In BCCs without STA, CK1-8, CK14 and CK17 antibodies were expressed by tumour tissue in all biopsy specimens. In the BCCs with STA, tumour tissue was immunoreactive always with CK1-8 and CK17 antibodies, and commonly immunoreactive with anti-CK 14 antibody. In the epidermis overlying tumour tissue, there was positive immunoreactivity with anti-CK 1-8, CK 5/6/18, CK 10 and CK 14 antibodies in all biopsy specimens. Anti-CK 17 antibody was also positive in 17 biopsy specimens. STA is immunoreactive with anti-CK1-8 in all specimens. There was mild staining with anti-CK5/6/18 and with anti-CK19 whereas no immunoreactivity with anti-CK10 and CK18 antibodies was found. In conclusion, we could not find a significant CK expression difference between BCCs with and without STA. Weak positivity and a few number of CKs were shown in STA when compared with those of BCC and epidermis overlying tumour tissue expressing the more variable CKs. Interestingly, although CKs coexpressed in pairs consisting of one basic and one acidic CK, we detected predominantly basic CKs in STA.

A study of cytokeratin profiles in localized cutaneous amyloids

The major component of localized cutaneous amyloids may be derived from cytokeratin (CK). However, the CK profiles of primary cutaneous amyloidosis (PCA) and secondary cutaneous amyloidosis (SCA) remain obscure. Paraffin-embedded sections of skin tissue from 64 patients with PCA, 111 with SCA and 3 with systemic amyloidosis were analyzed immunohistochemically using 12 different polyclonal or monoclonal anti-CK antibodies (34betaE12, MNF116, LP34, AE1/AE3, anti-CK1, CK5, CK6, CK7, CK10, CK14, CK16 and CK17). In addition, frozen skin tissues from 12 patients with PCA were analyzed for comparison with the paraffin-embedded tissue. In all 64 PCA paraffin sections, the amyloid deposits were immunopositive for anti-CK5 antibody and 34betaE12. In all 12 frozen sections of PCA, the amyloid deposits were immunopositive for anti-CK5 antibody, 34betaE12, MNF116 and LP34, and seven (58.3%), three (25%) and one (8.3%) were immunopositive for anti-CK1, CK14, and CK10 antibodies, respectively. In all SCA sections, the amyloid deposits were immunopositive for CK5 and 34betaE12. In addition, MNF116 immunolabeled amyloids of all sections from patients with basal cell carcinoma and trichoepithelioma, and MNF116 and LP34 immunolabeled amyloids of sections from patients with porokeratosis. Our results indicate that CK5 is the major CK present in the amyloid deposits of PCA and SCA, and "amyloid-K" is mainly derived from basal keratinocytes.

Cytokeratin expression in lichen amyloidosus and macular amyloidosis

AIM

To understand the role of epidermal cells in the pathogenesis of lichen amyloidosus (LA) and macular amyloidosis (MA).

METHODS

We carried out immunohistochemical investigations on cytokeratins (CKs) in amyloid deposits in formalin-fixed and paraffin-embedded tissue specimens from eight persons with LA and 12 with MA. The primary antibodies of CK1-8 (AE3), CK10 (DEK-10), CK14 (LL002), CK17 (E3), CK18 (DC10), CK19 (KS19.1), CK5/6/18 (LP34) and CK8/18 (5D3) were used in the study.

RESULTS

In amyloid deposits, immunoreactivity with only two monoclonal antibodies (CK1-8 and CK5/6/18) was observed in 14 cases (eight LA and six MA), confirming the hypothesis that epidermal cells participate in amyloid formation of LA and MA.

COMMENTS

All of the CKs detected in amyloid deposits were basic type (type II). It seems plausible either that acidic CKs might be degraded faster than basic types in amyloidogenesis or that paraffin-embedded tissue specimens are less sensitive than frozen tissue sections. The results of our study suggest that when paraffin-embedded specimens are investigated by immunohistochemical methods, CK5 antibody is useful in the diagnosis of LA and MA.

Immunohistochemical study of cytokeratins in amyloid deposits associated with squamous cell carcinoma and dysplasia in the oral cavity, pharynx and larynx

The frequency of amyloid deposits associated with squamous cell carcinoma (SCC) and dysplasia in the oral cavity, pharynx and larynx was examined. In addition, the origin of amyloid proteins by immunohistochemical staining with a panel of anticytokeratin monoclonal antibodies was investigated. Amyloid deposits were found in eight of 73 (11.0%) SCC and one of seven (14.3%) dysplasias in the oral cavity, in eight of 22 (36.4%) SCC and zero of two (0%) dysplasias in the pharynx, and in 22 of 37 (59.5%) SCC and four of 10 (40.0%) dysplasias in the larynx. Eight of 12 different cytokeratin (CK) antibodies reacted with these deposits: 34 beta E12 (CK1, -5, -10, -14) reacted with amyloid deposits in 19 of 19 cases (100%), LL002 (CK14) in eight of 18 cases (44.4%), MNF116 (CK5, -6, -8, -17) in eight of 19 cases (42.1%), D5/16B4 (CK5, -6) in five of 18 cases (27.8%), DE-K10 (CK10) in four of 17 cases (23.5%), RCK108 (CK19) in three of 18 cases (16.7%), 34 beta B4 (CK1) in three of 19 cases (15.8%) and AE8 (CK13) in two of 17 cases (11.8%). These antibodies always reacted with the cytoplasm of squamous cell lesions. Amyloid deposits in two cases contained a CK5 and CK14 pair, and in another two cases they contained both a CK5 and CK14 pair, and a CK1 and CK10 pair. Anti-CK antibodies, including OV-TL12/30 (CK7), c-51 (CK8), DC10 (CK18) and IT-Ks20.8 (CK20) did not react with the amyloid deposits. We conclude that the amyloid deposits associated with SCC or dysplasia in the oral cavity, pharynx or larynx were derived from CK of cancer cells and that some amyloid deposits might be assembled by two or more different CK.

Advanced glycation end product-modified beta2-microglobulin is a component of amyloid fibrils of primary localized cutaneous nodular amyloidosis

Primary localized cutaneous nodular amyloidosis is a rare form of cutaneous amyloidosis. Amyloid fibrils in primary localized cutaneous nodular amyloidosis have been reported to be originated from immunoglobulin light chains. Immunohistochemical studies on the lesional skins of four patients with primary localized cutaneous nodular amyloidosis demonstrated that amyloid deposits of all cases showed a positive reaction with the antibodies for beta2-microglobulin and advanced glycation end products as well as immunoglobulin light chain (kappa or lambda). No beta2-microglobulin and advanced glycation end product immunoreactivity was found in the amyloid deposits of other primary localized cutaneous amyloidosis (lichen amyloidosis and macular amyloidosis). Double immunofluorescence study of the lesional skin of primary localized cutaneous nodular amyloidosis showed that anti-kappa light chain, anti-beta2-microglobulin and anti-advanced glycation end product antibodies mostly reacted with the same area of amyloid deposit. Amyloid proteins were sequentially extracted with distilled water from one case of primary localized cutaneous nodular amyloidosis and recovered in the five water-soluble fractions (fractions I-V). Immunoblot assay of amyloid fibril proteins demonstrated that immunoreactive polypeptides with anti-kappa light chain antibody (29 kDa) and with anti-beta2-microglobulin antibody (12 kDa) were detected in fractions I-V, whereas immunoreactive polypeptide with anti-advanced glycation end product antibody (12 kDa) was detected exclusively in fractions III-V but not in fractions I and II. Two-dimensional polyacrylamide gel electrophoresis revealed that 12 kDa polypeptide in fractions I and II was electrophoretically identical with authentic beta2-microglobulin and that beta2-microglobulin in fractions III-V was advanced glycation end product-modified beta2-microglobulin with more acidic pI value. These results indicate that beta2-microglobulin is another major component of amyloid fibrils in primary localized cutaneous nodular amyloidosis and that beta2-microglobulin in primary localized cutaneous nodular amyloidosis is partly subjected to the modification of advanced glycation end product.

Frictional dermal melanosis (lifa disease) over bony prominences

Seventy-one patients (70 females and one male) were studied. Their ages at presentation ranged from 16-43 years with a mean of 24.4 years. The duration of disease varied from three months to ten years with a median of 2.7 years. All patients were slim and had recorded using a washing agent (Lifa) during bathing with vigorous friction. Family history of the same disease was present in 11 (15.5%) patients. The pigmentation was brown-black with a rippled pattern and showed no contrast under Wood's light. The areas commonly affected were clavicles (71.8%), shins (36.6%), upper back (32.4%), Adam's apple (31%), lateral aspects of the arms (31%) and other areas. The histopathology of biopsies from 24 patients showed marked dermal melanosis. Amyloid deposits in the papillary dermis were present in one patient. This clinical and histopathological picture suggests that this common condition is related to frictional melanosis.

An immunohistochemical study of cytokeratins in skin-limited amyloidosis

The frequency of amyloid deposits in cases of seborrheic keratosis was investigated In addition, the origin of amyloid protein(s) in lichen amyloidosis, macular amyloidosis and seborrheic keratosis was studied by immunohistochemical staining using a panel of anti-cytokeratin (CK) monoclonal antibodies. Amyloid deposits were found in 41 of 327 specimens (12.5%) from 301 cases of seborrheic keratosis. Amyloid deposits in seborrheic keratosis reacted with 6 of 12 CK antibodies and in lichen and macular amyloidosis (20 specimens) reacted with 5 of 12 CK antibodies. In seborrheic keratosis, antibody DE-K10 (labeling CK10) reacted with amyloid in 17 of 36 cases, antibody 34betaE12 (labeling CK1, 5, 10, 14) reacted in 33 of 39 cases, and antibody MNF116 (labeling CK5, 6, 8, 17) reacted in 32 of 35 cases. Among 20 specimens from lichen and macular amyloidosis, the three antibodies reacted with amyloid in the following rates: 1 with antibody DE-K10, all 20 with antibody 34betaE12, and 6 with antibody MNF116. These results suggest that amyloid deposits in seborrheic keratosis and lichen and macular amyloidosis may derive from epidermal cytokeratins.

The amyloid deposit in calcifying epithelial odontogenic tumor is immunoreactive for cytokeratins

Calcifying epithelial odontogenic tumor, also known as Pindborg tumor, is a rare benign tumor with locally aggressive behavior. It is characterized by squamous epithelial cells, calcifications, and eosinophilic deposits that have been identified as amyloid. We report a case of calcifying epithelial odontogenic tumor and investigate the nature of the amyloid, using histologic, immunohistochemical, and ultrastructural studies. The amyloid was immunohistochemically negative for basement membrane components and positive for all cytokeratin stains performed (cocktail of cytokeratins 1, 5, 6, 8, 13, and 16, and cytokeratins AE1 and AE3). The amyloid stained focally in a glandular-like pattern, reminiscent of the epithelial glandlike structures of the tumor. We conclude that the amyloid is derived from filamentous degeneration of keratin filaments that originate from the tumor squamous epithelium. The keratin degeneration is part of a developmental or aging process that the tumor undergoes.

Cytokeratins in primary cutaneous amyloidosis

The expression of keratins was investigated immunohistochemically on formalin-fixed and snap-frozen primary cutaneous amyloidosis tissue with a panel of monospecific and polyspecific antikeratin antibodies, with recognized keratins K1, K5, K6, K7, K8, K10, K14, K16, K17, K18 and K19. Amyloid deposits in frozen sections of seven cases of macular amyloidosis and lichen amyloidosus always reacted with antibodies LP34 (labelling K5, K6 and K18), MNF 116 (labelling K5, K6, K8, K10, K17 and K18), and RCK 102 (labelling K5 and K8); frozen sections in one case each of the seven cases also reacted with antibodies LL001 (labelling K14), LP1K (labelling K7 and K17), and LP2K (labelling K19). In formalin-fixed sections of 13 cases of macular amyloidosis and lichen amyloidosus, amyloid deposits were labelled with LP34 in three sections, MNF 116 in four sections, LL020 (labelling keratins K5 and K6) in one section, and LP2K in two sections. In nodular primary cutaneous amyloidosis, amyloid deposits were not labelled with any antikeratin antibodies. These data confirm that amyloid in macular amyloidosis and lichen amyloidosus contains keratin epitopes, and suggests derivation of the fibrillar component from keratin intermediate filaments. Several different keratins appear to undergo conversion to amyloid. LP34, MNF 116 and RCK 102 antibodies, which have in common the labelling of keratin K5, may be useful in the diagnosis of macular and papular amyloidosis with frozen tissue sections.

Calcifying epithelial odontogenic tumours in small domesticated carnivores: histological, immunohistochemical and electron microscopical studies

Histological, immunohistochemical and electron microscopical studies revealed one feline and four canine calcifying epithelial odontogenic tumours in 115 oral tumours over a 10-year period. The tumours consisted of islands and sheets of odontogenic epithelium of varying size within a stroma of fibrous connective tissues. The tumour cells were pleomorphic with variable amounts of eosinophilic cytoplasm and large hyperchromatic, polymorphic nuclei with prominent nucleoli. Clusters of keratinized tumour cells ("shadow cells") were frequently seen within the islands and sheets. The multiple spherules of homogeneous eosinophilic material stained positively with Congo red and Dylon stains and produced an apple green birefringence under polarization microscopy, indicative of amyloid. Mineralized foci were scattered throughout the tumour masses and in the homogeneous spherules. Immunohistochemically, the tumour cells reacted with anti-human keratin antibody, but not with anti-human vimentin or anti-chicken desmin antibodies. The homogeneous spherules did not react with anti-human keratin, anti-human vimentin, anti-chicken desmin, anti-amyloid A, anti-laminin or anti-human collagen (type I, III, IV) antibodies. Ultrastructurally, the cytoplasm of tumour cells was abundant and contained a large number of electron-dense bundles of tonofilaments. The homogeneous spherules consisted of fine filaments measuring about 10-12 nm in diameter.

Localized cutaneous amyloidosis simulating lichen simplex chronicus

We report a case of localized cutaneous amyloidosis in a 42-year-old Japanese woman. Skin lesions were confined to the nuchal area, and the clinical appearance resembled that of lichen simplex chronicus. Our experience with this case indicates that, in cases presenting with persistent skin lesions simulating lichen simplex chronicus, amyloid should be specifically looked for in biopsy material.

Ubiquitinated cytokeratin inclusions in lichen amyloidosus: an immunohistochemical analysis

Eosinophilic hyaline inclusions were consistently seen in the perinuclear cytoplasm of suprabasal keratinocytes in lichen amyloidosus. The inclusions, negative with amyloid staining, were immunoreactive for ubiquitin and cytokeratin, and ultrastructurally showed aggregations of fine filaments of two sizes (central thin and peripheral thick). The thin filaments were the main component in the upper epidermal layer. Four monoclonal antibodies (AE1, AE3, KL1 and CAM5.2) and one antiserum (WSS) were used for characterizing cytokeratin expression. The AE1 antibody normally stained the basal cells, but in lichen amyloidosus basal staining mostly disappeared. Instead, groups of suprabasal keratinocytes were labeled, with AE1-reactive inclusions distributed therein. In contrast, the KL1 antibody, showing suprabasal staining, failed to react with the inclusions. The inclusions were weakly reactive with the AE3 and WSS antibodies, which stained all keratinocytes. The CAM5.2 antibody was unreactive. The subepidermal amyloid deposits were negative with all the antibodies. The inclusions were ubiquitinated especially in the granular layer. Immunoelectron microscopy disclosed that ubiquitin was more densely localized in the thin filaments than in the thick ones. This indicated that cytokeratin expression and metabolism are altered in the affected epidermis, and that ubiquitin functions in the process of degradation of abnormal cytokeratin filaments.

Localized amyloidosis in squamous cell carcinoma of uterine cervix: electron microscopic features of nodular and star-like amyloid deposits

An ultrastructural study of amyloid deposits in four cases of squamous cell carcinoma of uterine cervix was performed. The amyloid deposits reacted with anti-keratin antiserum on frozen sections. Amyloid deposits showed nodular (4 cases) and star-like forms (3 cases). Nodular amyloid deposits were composed of slightly whorled fibrils, measuring 7-10 nm in width. Some of them contained cellular debris and thicker, more electron-dense filaments than amyloid fibrils. In three cases, filamentous tumour cells and filamentous masses were observed together with amyloid. Star-like amyloid deposits were composed of bundles of straight amyloid fibrils. Some of the tumour cells in contact with star-like amyloid deposits had deep cytoplasmic invaginations, where closely packed amyloid fibrils were arrayed in parallel fashion. In addition, a few tumour cells had membrane-bound amyloid fibrils in the cytoplasm. It is suggested that nodular amyloid deposits are derived from the tumour cells through filamentous degeneration. Amyloid fibrils in star-like amyloid deposits are thought to be formed within the cytoplasm or in the vicinity of invaginated cytoplasmic membranes of the tumour cells.

Diffuse primary cutaneous amyloidosis

A case of extensive primary cutaneous amyloidosis exhibiting both macular and lichenoid lesions is reported. Lesions were arranged in a distinctive linear pattern covering much of the trunk and limbs, in places following Blaschko's lines. The coexistence of macular and lichenoid lesions suggests that this is an unusual variant of biphasic cutaneous amyloidosis.

BCC-associated amyloidosis with a peculiar pattern of deposition

An 83-year-old Japanese woman with lepromatous leprosy had been treated in a leprosarium. More than 10 years ago, she developed a dome-like brown tumor on the dorsum of the nose which showed the histology of basal cell carcinoma. The lesion was a well bordered, rounded tumor with tumor cell nests on its periphery extending toward the center as cords of tumor nest and with amyloid depositions between the cords. The tumor nests and amyloid lessened toward the center of the tumor, being replaced by collagen fibers. Amyloidosis showing this peculiar pattern of transition was reported with a review of published cases.

Lamina densa malformation involved in histogenesis of primary localized cutaneous amyloidosis

Skin lesions of lichenoid amyloidosis and macular amyloidosis were immunohistochemically investigated using five monoclonal antibodies against basement membrane zone (BMZ) components. A hemidesmosomal component did not contribute to amyloid deposits, but components of the lamina densa and anchoring fibrils were associated with amyloid deposits in the uppermost dermis. Immunoelectron microscopy revealed that these BMZ components were not only aggregated in the BMZ and dermis, but were also involved in the individual amyloid islets. The lamina densa was disrupted in the interface areas just above the amyloid deposits, where cytoplasm of the basal cells directly faced the aggregate of amyloid filaments. Aggregates of some BMZ components were continuous to the amyloid islets from the lamina densa area. These findings suggest that a lamina densa malformation is involved in amyloid production in the interface of the BMZ, and support the secretion theory rather than the fibrillar body theory of amyloidogenesis in these types of primary localized cutaneous amyloidosis.

Unusual manifestations of primary cutaneous amyloidosis in association with Raynaud's phenomenon and livedo reticularis

A patient with unusual manifestations of primary cutaneous amyloidosis, including macules, papules, oedematous plaques and urticarial lesions is described. Raynaud's phenomenon and livedo reticularis were an associated finding. During the acute phase, single doses of systemic corticosteroids resulted in an impressive, long-lasting improvement in cutaneous manifestations.

Macular and lichenoid amyloidosis: a possible secretory product of stimulated basal keratinocytes. An ultrastructural study

This study examined the histogenic pathways of amyloid formation in skin-limited amyloidosis. Skin biopsies taken from 10 cases of macular or lichenoid amyloidosis were studied with the light and electron microscope. Keratinocytes with filamentous degeneration were frequently encountered. They were normally eliminated either transepidermally through the surface or by macrophages at the dermoepidermal junction. Only occasionally was amyloid deposition observed to be associated with apoptotic keratinocytes undergoing filamentous change. On the other hand, small aggregates of amyloid were frequently observed at the dermoepidermal junction closely applied to healthy non-degenerate basal keratinocytes. The early appearance of amyloid at the dermoepidermal junction, its pattern of distribution and its intimate association with overlying active basal keratinocytes suggest that these fine, straight, interlacing fibrils may be a secretory product of stimulated basal keratinocytes.