Diffuse primary cutaneous amyloidosis

Two missense mutations in GPNMB cause autosomal recessive amyloidosis cutis dyschromica in the consanguineous pakistani families

BACKGROUND

Amyloidosis cutis dyschromica (ACD) is a rare variant of cutaneous amyloidosis. This disorder often clusters in families, and it has been suggested that genetic factors might be involved in its development.

OBJECTIVE

To identify the genetic causes of ACD, we recruited a consanguineous Pakistani family with multiple cases of ACD that display a recessive mode of inheritance.

METHODS

We performed whole-exome sequencing of samples from 7 members of this family, followed by bioinformatic and in silico analyses to identify the causative variant. For the replication study, we recruited a British family with Pakistani ancestry, and sequenced all exons of glycoprotein non-metastatic melanoma protein b (GPNMB) to identify mutations. We also investigated effects of the mutations on the stability of the GPNMB protein using the I-TASSER three-dimensional modeling tool.

RESULTS

We found a novel homozygous mutation, p.Gly363Val (c.1088 G>T), in GPNMB in all affected cases. In a replication study, another homozygous missense mutation in GPNMB, pIle174Met (c.522 C>G), was carried by the affected son. The two mutations were not observed in our in-house data set comprising 217 healthy Pakistani individuals or in The Genome Aggregation Database. Our structural modeling of GPNMB suggested that p.Gly363Val enhanced its stability, whereas p.Ile174Met caused instability.

CONCLUSIONS

This study reports two novel missense mutations in two Pakistani families that cause ACD. The mutations appear to influence GPNMB stability, as revealed by protein modeling.

Clinicopathological evaluation of patients with rippled pattern pigmentation of the skin: A single-center study

The aim of the present study was to investigate the clinical association between rippled pattern pigmentation and the positivity of histopathological analysis for amyloid. A total of 50 patients (90% women) with rippled pattern pigmentation referring to Dermatology Clinic of Shahid Faghihi Hospital, Shiraz, Iran, in 2015 participated in this study. Two biopsies were performed for all the cases from the most frequently affected sites. The specimens were evaluated for amyloid deposits with hematoxylin-eosin (H&E), Congo red (CR), and crystal violet (CV) stains. The upper back was the most frequently affected area in the patients. Family history (28%), atopy (14%), pruritus as a common finding (86%), and history of friction (54%) were positive. The prevalence of disease was higher in patients with skin photo Type 3. Amyloid deposit was not detected in most patients by these stains. No statistically significant difference was found between the amyloid positive cases stained with H&E, CR, and CV (p-value > 0.05). Only the difference in positive results between biopsy number 2 and the total biopsy (1 and 2) was significant (p-value < .05). In conclusion, it seems that it is useful to increase the number of biopsies and other more sensitive staining methods to detect small focal amyloid deposits.

The eye and the skin in nonendocrine metabolic disorders

As metabolism is controlled by the input of genes and the environment, metabolic disorders result from some disturbance in the interaction between genes and environmental factors. Many metabolic disorders consist in congenital enzyme deficiencies, also known as "inborn errors of metabolism," that may be disabling or cause severe illness and death and are predominantly inherited in an autosomal recessive fashion. The deposit in cells and tissues of storage substances from errors in metabolic processes may produce a wide variety of disorders affecting different organs and functions, with different degrees of severity, and often present around the time of birth or early childhood. Distinctive ocular and skin manifestations accompany many metabolic diseases and may provide clues for their diagnosis and evolution.

Systemic AL amyloidosis with unusual cutaneous presentation unmasked by carotenoderma

We present a case study of an elderly woman with systemic lambda-type AL amyloidosis that featured unusually extensive cutaneous involvement. The case initially presented with a sudden hyper β-carotenemia with carotenoderma that instigated the clinical examination including skin biopsy. A diagnosis of systemic amyloidosis was made. Immunohistochemistry and Western-blot analysis indicated the presence of lambda light chain proteins in skin amyloid deposits. However, notable co-deposition of wild-type apoA-I and transthyretin was observed which caused initial diagnostic confusion. Proteomic analysis of microdissected skin amyloid deposits by mass spectrometry confirmed lambda light chain proteins in amyloid deposits and co-deposition of apolipoprotein A-IV and serum amyloid P-component. The patient died from renal failure caused by amyloid nephropathy combined with analgesic nephropathy. The autopsy disclosed vascular, cardiac, renal and pulmonary amyloid deposition. While all amyloid deposits were positive for lambda light chain proteins, the immunodetection of apoA-I and transthyretin varied significantly among the visceral amyloid deposits. Although the patient exhibited a 1000-fold increase in serum β-carotene levels, only a mild increase in retinol and lutein concentrations was observed. Increased β-carotene values were also found in the liver and the skin. The mechanisms underlying this hyper β-carotenemia remain undetermined.

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.

Amyloidosis cutis dyschromica: a rare pigmentary disorder

Amyloidosis cutis dyschromica represents a rare type of primary cutaneous amyloidosis with few reported cases worldwide. It is characterized by asymptomatic, generalized hyperpigmentation with intermingled hypopigmented macules without atrophy or telangiectasia. We report herein a 19-year-old female who developed this pigmentary abnormality at 4 years of age. Her aunt and great grandfather also had similar skin pigmentation. An unusual finding in our patient was the presence of papules in addition to characteristic macules. Amyloid deposits were shown histopathologically in both dyschromic macules and papules.

New insight into mechanisms of pruritus from molecular studies on familial primary localized cutaneous amyloidosis

Macular and lichen amyloidosis are common variants of primary localized cutaneous amyloidosis (PLCA) in which clinical features of pruritus and skin scratching are associated with histological findings of deposits of amyloid staining on keratinous debris in the papillary dermis. Most cases are sporadic, but an autosomal dominant family history may be present in up to 10% of cases, consistent with a genetic predisposition in some individuals. Familial PLCA has been mapped to a locus on 5p13.1-q11.2 and in 2008 pathogenic heterozygous missense mutations were identified in the OSMR gene, which encodes oncostatin M receptor beta (OSMRbeta), an interleukin (IL)-6 family cytokine receptor. OSMRbeta is expressed in various cell types, including keratinocytes, cutaneous nerves and nociceptive neurones in dorsal root ganglia; its ligands are oncostatin M and IL-31. All pathogenic mutations are clustered in the fibronectin-III repeat domains of the extracellular part of OSMRbeta, sites that are critical for receptor dimerization (with either gp130 or IL-31RA), and lead to defective signalling through Janus kinase-signal transducers and activators of transcription, extracellular signal-regulated protein kinase 1/2 and phosphoinositide 3 kinase/Akt pathways. Elucidating the molecular pathology of familial PLCA provides new insight into mechanisms of pruritus in human skin, findings that may have relevance to developing novel treatments for skin itching. This review provides a clinicopathological and molecular update on familial PLCA.

Cutaneous amyloidosis associated with primary biliary cirrhosis

Primary cutaneous amyloidosis is defined as the deposition of amyloid in the skin in the absence of systemic involvement. The association between primary cutaneous amyloidosis and other diseases, although rare, has been documented for connective tissue disorders such as systemic sclerosis, systemic lupus erythematosus and rheumatoid arthritis. We report the case of a 41-year-old woman who developed primary biliary cirrhosis in association with primary cutaneous amyloidosis. This association has not been reported before in the literature.

Amyloidosis cutis dyschromica in two siblings

Amyloidosis cutis dyschromica (ACD), a rare distinct type of primary cutaneous amyloidosis was noted in two siblings: a 25-year-old male and his brother aged 20 years. It was characterized by reticulate hyperpigmentation with hypopigmented spots seen almost all over the body without any papulation. This familial disorder has been reported mostly from Japan. Our report of familial ACD is probably the first from India.

Lichen amyloidosis, ankylosing spondylitis and autoimmune thyroiditis: coincidence or association?

Primary localized cutaneous amyloidosis (PLCA) is characterized by the deposition of amyloid in a previously apparently normal skin with the absence of other systemic or cutaneous disorder. Although ankylosing spondylitis may be associated with secondary systemic amyloidosis, no reports have been found showing the association of this disease with PLCA. In addition, the association of PLCA with autoimmune thyroiditis has not been previously reported. We report a concomitant occurrence of lichen amyloidosis, ankylosing spondylitis and autoimmune thyroiditis in a caucasian woman.

Cutaneous deposition diseases. Part I

The cutaneous deposition disorders are a group of unrelated conditions characterized by the presence of either endogenous or exogenous substances within the dermis or the subcutis. Part I of this two-part series will focus on metabolic processes involved in the endogenous deposition in the various forms of amyloidosis, porphyria, colloid milium, and lipoid proteinosis. We will also review the clinical, histologic, biochemical, and ultrastructural findings relevant to each disorder. Basic mechanisms of pathogenesis, diagnostic modalities, and treatment options are also discussed.