Nonuremic Calciphylaxis Associated With Histologic Changes of Pseudoxanthoma Elasticum

Cutaneous vascular calcification. Peri-eccrine calcification as a diagnostic key for calciphylaxis

BACKGROUND

Attempts have been made to establish discriminative criteria between classic calciphylaxis (CPX) and those cases in which cutaneous vascular calcification (CVC) represents an incidental finding (epiphenomenon).

METHODS

Retrospective, observational cohort study of patients with CVC with the aim of distinguishing clinicopathological features between CVC as classic CPX (CVC in cutaneous lesions with erythemato-violaceous plaques with or without ulceration) or as epiphenomenon (CVC in cutaneous lesions with known diagnosis). Different clinicopathological parameters and presence of perieccrine calcification and pseudoxanthoma-elasticum (PXE)-like changes were evaluated.

RESULTS

Sixty-six patients were studied. The CPX group showed a significantly higher percentage of renal failure, hypertension, altered laboratory parameters, painful lesions and mortality rate. Histopathologically, the CPX group was associated with more than one vessel per field involved with subintimal concentric calcification and perieccrine calcification (observed exclusively in CPX group), while PXE changes, although more frequent in the CPX group, were also observed in the epiphenomenon group.

CONCLUSIONS

Perieccrine calcification and the presence of more than one vessel per field involved by concentric pattern calcification could be used as a diagnostic marker of CPX. Although PXE-like changes are not an exclusive marker, they could suggest CPX diagnosis. This article is protected by copyright. All rights reserved.

Diagnosing Calciphylaxis: A Review With Emphasis on Histopathology

Calciphylaxis is a cutaneous vasculopathy with high morbidity and mortality characterized by vascular intimal fibrosis, calcification, stenosis, thrombosis, and eventual tissue death due to ischemia. Histopathologic diagnosis is often difficult, frequently necessitating multiple tissues samples due to lack of specific histopathologic features and subtle changes on biopsies of early lesions. In this study, we review the reported clinical and histopathologic features of calciphylaxis, correlating them with relevant imaging, ancillary studies, and pathophysiology. Although many histopathologic changes seen in calciphylaxis are also reported in other conditions (eg, Mönckeberg sclerosis, lupus panniculitis, pancreatic panniculitis, and peripheral artery disease), calcification of subcutaneous small vessels, thrombosis and/or ischemic changes, pseudoxanthoma elasticum-like changes in the subcutis, and perieccrine calcification may serve as helpful clues. von Kossa and Alizarin red stains can assist in the identification of subtle calcification. Netlike calcification of the affected blood vessels on imaging further supports the diagnosis. Studies into the pathophysiology of calciphylaxis are ongoing and will hopefully facilitate the development of additional diagnostic adjuncts to increase sensitivity and specificity for the diagnosis of this disease.

Clinicopathologic Features and Calcium Deposition Patterns in Calciphylaxis: Comparison With Gangrene, Peripheral Artery Disease, Chronic Stasis, and Thrombotic Vasculopathy

Diagnosis of calciphylaxis is crucial, yet its distinction from other vascular diseases can be challenging. Although vascular calcification and thrombosis are hallmarks of calciphylaxis, the incidence and patterns of these features in other vascular diseases have not been well characterized. The specificity of fine calcium deposits in vessel walls (identifiable on von Kossa [VK] stain only) and other extravascular calcifications is not entirely clear. We retrospectively examined the clinicopathologic features in calciphylaxis (n=27), gangrene and viable skin at amputation margin (n=20 each), chronic stasis (n=22), and thrombotic vasculopathy (n=19) to identify useful discriminators. Calcification of subcutaneous small vessels appreciable on hematoxylin and eosin stain was relatively specific for calciphylaxis, although sensitivity was low (56%). VK detected fine calcium deposits in vessel walls not appreciable on hematoxylin and eosin, however, specificity was limited by frequent finding of similar deposits in peripheral artery disease. Combining calcium deposits detected by VK and thrombosis of subcutaneous small vessels resulted in optimal sensitivity (85%) and specificity (88%) for calciphylaxis. Similar observations applied to medium-sized vessel calcification. Calcification of eccrine gland basement membranes, elastic fibers, and perineurium did not effectively distinguish calciphylaxis from other groups. Diffuse dermal angiomatosis was exclusively found in calciphylaxis in this study. In conclusion, VK is useful in enhancing the detection of vascular calcification and avoiding the false-negative diagnosis, but this finding requires concomitant subcutaneous small vessel thrombosis to support a diagnosis of calciphylaxis. Diffuse dermal angiomatosis should increase suspicion for underlying calciphylaxis and prompt deeper sampling in the appropriate clinical setting.

Pseudoxanthoma Elasticum: An Interesting Model to Evaluate Chronic Kidney Disease-Like Vascular Damage without Renal Disease

Background

Pseudoxanthoma elasticum (PXE; OMIM 264800) is an inherited multisystem disorder associated with accumulation of mineralized and fragmented elastic fibers in the skin, vascular walls, and brush membrane in the eye. Carriers exhibit characteristic lesions in the cardiovascular system, and peripheral and coronary arterial disease as well as mitral valvulopathy often present as a cardiovascular feature of this disease. PXE and chronic kidney disease (CKD) share some common patterns in the vascular damage and in therapeutic approaches as well.

Summary

To date, treating PXE has focused more on careful follow-up examinations with retinal specialists and cardiologist, avoiding long-term anticoagulation. Like CKD, maintaining a low-calcium diet, increasing dietary magnesium, and administering phosphate binders such as aluminum hydroxide or sevelamer may yield a modest benefit. Recently, 4-phenylbutyrate acid (4-PBA) has demonstrated a maturation of ABCC6 mutant effects into the plasma membrane. Moreover, in a humanized mouse model of PXE, 4-PBA administration restored the physiological function of ABCC6 mutants, resulting in enhanced calcification inhibition and thus a promising strategy for allele-specific therapy of ABCC6-associated calcification disorders.

Key Message

Vascular compromise in PXE patients share some components similar to CKD.

What's New in Dermatopathology: Inflammatory Dermatoses

Inflammatory skin diseases encompass a vast array of conditions. The field continues to expand and evolve with resurgence of conditions, through newly recognized medication adverse effects, and via more detailed descriptions of known dermatoses. The importance of clinicopathologic correlation and an up to date knowledge of dermatologic conditions cannot be overstated. This review focuses on an array of recent important developments in the histologic diagnosis of inflammatory conditions that affect the skin.

Calciphylaxis in Patients With Normal Renal Function: A Case Series and Systematic Review

OBJECTIVE

To define concomitant risk factors, treatment, and outcomes for patients with nonnephrogenic calciphylaxis (NNC).

PATIENTS AND METHODS

A retrospective review of Massachusetts General Hospital (MGH) medical records (January 1, 2014, through February 29, 2016) and a systematic literature review of PubMed, Google Scholar, EMBASE, MEDLINE, and CENTRAL (August 1, 1970, through July 31, 2016) were performed. Demographic characteristics and concomitant features were summarized and compared between patients with different lesion characteristics. Outcomes (lesion improvement and mortality) and their predictors were analyzed.

RESULTS

Nine patients (median age, 72 years [interquartile range (IQR), 44-82 years]; 78% women; 89% white race) were identified through MGH records. The literature review identified 107 patients (median age, 60 years [IQR, 49-72 years]; 77% women; 86% white race). Vitamin K antagonism and obesity were the most common concomitant factors. In the literature review, lower age (P<.001) and higher body mass index (P=.03) were associated with the central location of lesions, whereas vitamin K antagonism was associated with the peripheral location (P=.009). In the MGH series, median survival was 24.0 months (95% CI, 7.8-36.0 months), and 33% (95% CI, 14%-60%) had lesion improvement by 6 months. In the literature review, median survival was 4.2 months (95% CI, 1.9-5.9 months), median time to lesion improvement was 5.9 months (95% CI, 3.9-8.9 months), and none of the treatments were associated with lesion improvement or survival.

CONCLUSION

This description of concomitant traits may augment an earlier recognition of NNC. Future research is needed to investigate NNC pathogenesis and treatments.

Pseudoxanthoma elasticum-like changes in nonuremic calciphylaxis: Case series and brief review of a helpful diagnostic clue

Calciphylaxis is a rare syndrome of vascular calcification with thrombosis that occurs most often in patients with end-stage renal disease, and it frequently portends a guarded prognosis. Rarely, nonuremic calciphylaxis (NUC) may occur; in this context, a strongly supportive histology is crucial in establishing the diagnosis. Herein, we describe 2 cases of NUC associated with pseudoxanthoma elasticum-like changes, identified in both initial nondiagnostic and subsequent diagnostic biopsy specimens. This unusual but helpful histologic finding may support the early diagnosis and treatment of a potentially life-threatening disease in the context of subtle histopathologic vascular changes or in the absence of classic clinical or laboratory findings.

Extraosseous calcification in end-stage renal disease: from visceral organs to vasculature

In earlier days, periarticular accumulations of calcium phosphate causing tumor-like depositions were considered the result of passive precipitation and referred to as metastatic calcifications. From sophisticated computer tomographic studies and growing insight, we have learned that calcifications in the cardiovascular system are far more threatening and in fact one of the most important sequela of end-stage renal disease. The histologic characteristic of uremia-related calcification is arteriosclerosis of the media. In addition, there is atherosclerosis of the intima, due to the high prevalence of classic cardiovascular risk factors in renal disease. The two vascular features can frequently exist at different sites in the vasculature. Novel diagnostic techniques are helping to elucidate the pathogenetic mechanisms of active conversion of vascular smooth muscle cells to osteochondritic cells. Through this process, extensive calcification of the central and peripheral vasculature ensues, influenced by different promotors and inhibitors. Calciphylaxis is a special form of extraosseous calcification leading to skin necrosis. The factors that trigger the development of calciphylaxis are not completely understood, but this syndrome shares part of the pathophysiologic basis of extraosseous calcification in general. However, the therapeutic approach must be prompt and aggressive, because of the poor prognosis. Frequently, a fatal outcome cannot be avoided in calciphylaxis.