Amyloidosis cutis dyschromica: four cases from two families

Dermoscopy of Amyloidosis Cutis Dyschromica

Amyloidosis cutis dyschromica is a very rare form of primary cutaneous amyloidosis characterized by prepubertal onset of hyper and hypopigmented spots and amyloid deposits in the papillary dermis. We report two cases of this condition highlighting its dermoscopic findings.

Primary Localized Cutaneous Amyloidosis Affecting Female Individuals of a Pakistani Pedigree

Primary localized cutaneous amyloidosis is a group of rare conditions where amyloid deposition is limited to the skin without systemic manifestations. Most cases are sporadic; however, mutations in the oncostatin M receptor (OSMR) and interleukin-31 receptor A (IL31RA) genes can cause a familial form of the condition in up to 10% of cases. Here, we describe a family in which 8 female individuals are affected by either macular amyloidosis or amyloidosis cutis dyschromica. To the best of our knowledge, a sex-specific expression or the coexistence of 2 different phenotypes of primary localized cutaneous amyloidosis in 1 pedigree has not yet been reported.

Loss of GPNMB Causes Autosomal-Recessive Amyloidosis Cutis Dyschromica in Humans

Amyloidosis cutis dyschromica (ACD) is a distinct form of primary cutaneous amyloidosis characterized by generalized hyperpigmentation mottled with small hypopigmented macules on the trunks and limbs. Affected families and sporadic case subjects have been reported predominantly in East and Southeast Asian ethnicities; however, the genetic cause has not been elucidated. We report here that the compound heterozygosity or homozygosity of GPNMB truncating alleles is the cause of autosomal-recessive ACD. Six nonsense or frameshift mutations were identified in nine individuals diagnosed with ACD. Immunofluorescence analysis of skin biopsies showed that GPNMB is expressed in all epidermal cells, with the highest staining observed in melanocytes. GPNMB staining is significantly reduced in the lesional skin of affected individuals. Hyperpigmented lesions exhibited significantly increased amounts of DNA/keratin-positive amyloid deposits in the papillary dermis and infiltrating macrophages compared with hypo- or depigmented macules. Depigmentation of the lesions was attributable to loss of melanocytes. Intracytoplasmic fibrillary aggregates were observed in keratinocytes scattered in the lesional epidermis. Thus, our analysis indicates that loss of GPNMB, which has been implicated in melanosome formation, autophagy, phagocytosis, tissue repair, and negative regulation of inflammation, underlies autosomal-recessive ACD and provides insights into the etiology of amyloidosis and pigment dyschromia.

Clinical and Genetic Review of Hereditary Acral Reticulate Pigmentary Disorders

Reticulated pigmentation is a unique pigmentary change caused by a heterogeneous group of hereditary and acquired disorders. This pigmentation is characterized by a mottled appearance, with lesions that vary in size and pigmentary content. This review discusses the hereditary group of the reticulated pigmentation disorders, such as dyschromatosis symmetrica hereditaria, dyschromatosis universalis hereditaria, and reticulate acropigmentation of Kitamura. The clinical presentation and histopathological features often overlap, making diagnosis difficult. However, each of these hereditary conditions possesses a unique genetic mutation, and genetic analysis is thus more useful in the diagnosis of these conditions. This article delivers an update regarding the clinical features, detailed histopathological description, and genetic information concerning hereditary reticulate pigmentary disorders and aims to provide useful background for use by clinical dermatologists and histopathologists when approaching this group of hereditary disorders.

Amyloidosis Cutis Dyschromica: A Rare Reticulate Pigmentary Dermatosis

We are reporting a rare case of amyloidosis cutis dyschromica in a 41-year-old man. This is a rare form of primary cutaneous amyloidosis characterized by reticulate pigmentation with hypopigmented and hyperpigmented macules, onset in childhood, familial tendency in some, occasional mild itching and deposition of amyloid in the papillary dermis. Our case also had multiple bilaterally symmetrical hyperpigmented keratotic papules abutting the axillary vault resembling those seen in Dowling–Deogs disease. The other unusual feature in this patient was the strong family history of vitiligo, which we are unable to explain. We have also tried to explain the mechanism leading to the hyperpigmentation and hypopigmentation in amyloidosis cutis dyschromica.

Amyloidosis cutis dyschromica in two siblings and review of the epidemiology, clinical features and management in 48 cases

Amyloidosis cutis dyschromica (ACD) is a rare form of primary cutaneous amyloidosis (PCA). There is a paucity of information in the dermatology literature to guide its diagnosis, investigation and treatment. We present two siblings with ACD and summarise the epidemiology, clinical features, natural history and treatments in 48 cases of ACD from the literature. Familial cases were more common (37) than sporadic cases. ACD is predominantly reported in those of East and South-East Asian ethnicity (63%). The mean age of onset was 6 years in familial cases, and 23 years in sporadic cases. The clinical features of familial and sporadic ACD do not differ substantially. Pruritus was the only symptom, and was reported in 19% of all cases. There were no reported ACD cases with systemic amyloidosis. Acitretin was reported to result in improvement in seven of 10 patients treated. Routine investigation for systemic involvement is not necessary. Acitretin may be helpful.

Amyloidosis cutis dyschromica

Background

Amyloidosis cutis dyschromica is a rarely documented variant of cutaneous amyloidosis. To date, only 26 cases have been reported.

Objective

The purpose of this study was to improve the clinical and histopathological data for this variant of amyloidosis and to highlight the immunohistochemical features of the disease. The published cases were also reviewed.

Methods

We performed a retrospective review of patients with amyloidosis cutis dyschromica in a single centre. The clinical, histopathological and immunohistochemical features were documented and analysed.

Observations

We described 10 cases of amyloidosis cutis dyschromica. Six of them were female. Five patients were from the same family, and the other 5 were sporadic. The distinguishing features of the clinical presentation included generalised mottled hyper- and hypopigmented macules, which were asymptomatic or mild pruritic. The typical onset of the lesions occurred in childhood (n = 7) and occasionally after puberty (n = 3). No evidence of systemic amyloidosis deposition was observed in these cases of amyloidosis cutis dyschromica. Amyloid deposits were observed in the papillary dermis and were positive for the Congo red stain. An immunohistochemical study showed that the amyloid expresses cytokeratins CK34βE12 and CK5/6.

Conclusions

We described the largest series of amyloidosis cutis dyschromica to date and reviewed the published patients. This rare disease is featured by generalised mottled hyper- and hypopigmented lesions, and it is a rare variant of primary cutaneous amyloidosis without evidence of systemic amyloid deposition. Positive staining for the cytokeratins CK34βE12 and CK5/6 in amyloidosis cutis dyschromica suggests that the amyloid is derived from keratinocytes.

Infancy- and childhood-onset dyschromatoses

The dyschromatoses are a group of pigmentary disorders characterized clinically by mixed and often guttate hypopigmented and hyperpigmented lesions. There are many conditions that present with dyschromatosis, including genodermatoses, inflammatory skin diseases, infections, drug and chemical use, and nutritional disorders. Some conditions have extracutaneous features. Poikiloderma (a combination of hypo- and hyperpigmentation with telangiectasia and atrophy) must be excluded. In this article, we describe the dyschromatoses typically presenting in infancy and childhood, most of which are genodermatoses. The approach we have taken in classifying them is based on organ involvement. We hope this article will serve as a guide for dermatologists to the recognition of these uncommon conditions.

Amyloidosis cutis dyschromica associated with atypical Parkinsonism, spasticity and motor weakness in a Pakistani female

Amyloidosis cutis dyschromica is a rare form of cutaneous amyloidosis in which there is deposition of keratinocyte-derived amyloid with involvement of almost the entire integument, leading to diffuse dyschromia without associated systemic abnormalities. We report the case of a 40-year-old female who presented with the onset of diffuse hyperpigmentation shortly after birth, which was followed by the widespread development of numerous 2-5 mm hypopigmented macules. Biopsy of the one of these macules revealed eosinophilic globular material in the papillary dermis with Congo red birefringence which also stained positively for high-molecular weight cytokeratin. Electron microscopy confirmed the presence of 11 nm hollow fibrils, consistent with amyloid. Similar clinical changes were noted in a younger male sibling. Both patients also suffered from an unexplained neurological disorder characterized by atypical Parkinsonism, spasticity and motor weakness. This association has not been shown before and may represent a heretofore unreported contiguous gene syndrome.

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.

Amyloidosis cutis dyschromica in two female siblings: cases report

Background

Cutaneous amyloidosis has been classified into primary cutaneous amyloidosis (PCA, OMIM #105250), secondary cutaneous amyloidosis and systemic cutaneous amyloidosis. PCA is the deposition of amyloid in previously apparent normal skin without systemic involvement. Amyloidosis cutis dyschromica (ACD) is a rare distinct type of PCA. Here, the unique clinical and histological findings of two Chinese female siblings with ACD were described.

Cases presentations

Patient 1 was a 34-year-old female, presented with mildly pruritic, diffuse mottled hyperpigmentation and hypopigmentation. The lesions involved all over the body since she was 10 years old. There were a few itchy blisters appearing on her arms, lower legs and truck, especially on the sun-exposed areas in summer. Some hypopigmented macules presented with slight atrophy. Patient 2 was 39-year-old, the elder sister of patient 1. She had similar skin lesions since the same age as the former. The atrophy and blisters on the skin of the patient with amyloidosis cutis dyschromica have not been described in previous literature. Histological examinations of the skin biopsies taken from both patients revealed amyloid deposits in the whole papillary dermis. Depending on the histological assessment, the two cases were diagnosed as amyloidosis cutis dyschromica.

Conclusion

The two cases suggest that the atrophy and blisters may be the uncommon manifestations of amyloidosis cutis dyschromica. It alerts clinicians to consider the possibility of ACD when meeting patients with cutaneous dyschromia. Skin biopsy is essential and family consultation of genetic investigation is very important in such cases.