Differential staining pattern of lysozyme in palisading granulomas: an immunoperoxidase study

Granuloma annulare: Clinical and histologic variants, epidemiology, and genetics

Granuloma annulare (GA) is a poorly understood condition characterized by a set of clinical morphologic variants with 2 predominant histopathologic patterns of inflammation. This review provides a comprehensive overview of the available information about the clinical variants and histopathologic features, current epidemiologic data, and potential genetic underpinnings of GA. Much of the current understanding of GA is based on retrospective studies, case series, and case reports; this review aims to synthesize the available information and present it clearly for practicing dermatologists.

Diagnostic immunohistochemistry through Rosai-coloured glasses

Over the past three decades, Immunohistochemistry has materially changed the practice of diagnostic surgical pathology. Foundational observations in this field were critical to a reasoned assessment of both the risks and opportunities that immunohistochemistry afforded the surgical pathologist, and our current practice draws heavily on those early assessments. As we collectively look to and acknowledge those who recognized the value of this technique and who helped guide its development as a companion to (not a replacement for) histomorphologic evaluation, we are drawn to those whose mastery of detail and ability to draw common patterns from seemingly unrelated phenomena helped define the diagnostic power of immunohistochemistry. The focus of this review is on one individual, Dr. Juan Rosai, whose contributions transcend the simple linkage of molecular observations to morphology, recognizing novel patterns in both form and color (the latter often the lovely shades of diaminobenzidine), seemingly viewing our diagnostic world at times through an entirely different lens. By looking at Dr. Rosai's early work in this field, reviewing a selection of his seminal observations, particularly in the Immunohistochemistry of thyroid and thymic neoplasia, revisiting how his special insight is often guided by the work of the early masters of morphology, and how his mentorship of others has helped shaped academic surgical pathology practice, perhaps we can get a glimpse through that lens.

Colocalization of C4d deposits/CD68+ macrophages in rheumatoid nodule and granuloma annulare: immunohistochemical evidence of a complement-mediated mechanism in fibrinoid necrosis

Rheumatoid nodule (RN) represents a palisading granuloma with central fibrinoid necrosis, which is not only a classical manifestation of rheumatoid arthritis (RA) and part of the American College of Rheumatology (ACR)-criteria, but also is its diagnostic hallmark. The pathogenesis of RN is still not fully understood. At present, only data on serum analyses indicating a complement-mediated pathogenesis in the development of RA are available. Equivalent examinations for RN have not yet been performed. Granuloma annulare (GA) represents another type of palisading granuloma. A special subtype of GA, subcutaneous GA (SGA), is an important differential diagnosis to RN. Therefore, our aim was to examine RN and SGA regarding the complement deposition (C4d) by immunohistochemical means. All RN and GA were stained by hematoxylin/eosin and different special stains. In addition, all specimens were stained immunohistochemically with antibodies against CD68. Five GA and five RN were analyzed immunohistochemically with antibodies against C4d and CD68, and evaluated using single- and doublestaining immunohistochemistry. All RN and GA displayed depositions of C4d within their central necroses and between the surrounding palisading macrophages. Most importantly, C4d/CD68 double staining was visible in the palisading macrophages next to the necroses, while macrophages in the periphery were negative for C4d but positive for CD68. The main difference between RN and GA was a quantitative phenomenon with less positively reacting macrophages in a more incomplete palisade in GA. The positive reactions of all central necroses to C4d and colocalization of CD68 and C4d suggest that a complement-mediated mechanism may be operative in the formation of fibrinoid necrosis. This mechanism may be involved in any form of "fibrinoid necrosis", since no different patterns of C4d/CD68 expression could be observed in GA. This may explain why RG/GA are not distinguishable morphologically.

[Differential diagnosis of rheumatoid granuloma]

Rheumatoid granuloma (RG) is histomorphologically defined as a subcutaneous palisading granuloma with central fibrinoid necrosis. Clinically, it presents as a nodule typically localized at pressure points near the joints. From the rheumatic pathological point of view, the main diagnostic challenge is the differentiation of RG from granuloma anulare, especially if clinical information on the site of removal, known diseases, duration of illness, medication and existing American College of Rheumatology (ACR) criteria are missing. Other granulomatous lesions, such as mycobacterial infections, foreign body granulomas, necrobiosis lipoidica or sarcoidosis, can be differentiated from RG by histopathological criteria or by additional examinations such as pathogen specification or PCR. An immunohistochemical marker for the differential diagnosis of granulomas is not yet available. Diagnosis is based on conventional H-E staining, alcian blue-PAS staining, polarizing analysis or PCR. In the following article, the most important granulomatous entities in the differential diagnosis of RG are introduced and the main diagnostic characteristics are discussed.

Histological and immunohistochemical study of granuloma annulare and subcutaneous granuloma annulare in children

BACKGROUND

The aim of this study was to investigate the histological and immunohistochemical features of granuloma annulare (GA) in comparison to deep granuloma annulare (DGA) and granulomatous dermatoses (GDs).

METHODS

Our material comprised 13 GA, 8 DGA and 1 atypical granuloma annulare (AGA) in a child with primary immunodeficiency, 10 cases of nonspecific GDs and 1 case of sarcoidosis with cutaneous involvement. The immunohistochemical streptavidin-biotin-Horseradish peroxidase (HRP) analysis was performed on paraffin sections for the detection of CD68/KP-1, CD68/anti-human CD68 clone PGM1 (PGM1), lysozyme, S-100 protein, CD1a, CD3, CD20/L-26, CD4 and CD8.

RESULTS

All 13 GA were characterized by typical palisading and interstitial granulomas. In 6 cases, the lesion extended to the subcutaneous fat, while a considerable perivascular lymphocytic infiltrate without any signs of vasculitis was observed in 10 cases. The DGA were located to the deep dermis and subcutaneous fat, showing palisading granulomas with central necrobiosis. Immunohistochemistry revealed a broad intense expression of CD68/PGM1 in the histiocytic population in all cases, a constant but fainter detection of CD68/KP-1 and a variable one of lysozyme. T-cell markers (CD3, CD4 and CD8) were mainly detected in the perivascular lymphocytic infiltrate of GA and DGA, with CD4+ T lymphocytes predominating over CD8+ in GA and DGA, while CD8+ T lymphocytes was the predominant population in AGA.

CONCLUSIONS

CD68/PGM1 is a sensitive and reliable histiocytic marker in confirming the histiocytic nature of equivocal GA and DGA, but the histiocytic immunoprofile is of no particular usefulness in differentiating GA from other GD.

Collagenolytic (necrobiotic) granulomas: part 1 - the ‘blue’ granulomas

A collagenolytic or necrobiotic non-infectious granuloma is one in which a granulomatous infiltrate develops around a central area of altered collagen and elastic fibers. The altered fibers lose their distinct boundaries and exhibit new staining patterns, becoming either more basophilic or eosinophilic. Within the area of altered collagen, there may be deposition of acellular substances such as mucin (blue) or fibrin (red), or there may be neutrophils with nuclear dust (blue), eosinophils (red), or flame figures (red). These color distinctions can be used as a simple algorithm for the diagnosis of collagenolytic granulomas, i.e. "blue" granulomas vs. "red" granulomas. Eight diagnoses are included within these two groupings, which are discussed in this two-part article. In this first part, the clinical presentation, pathogenesis, and histologic features of the "blue" collagenolytic granulomas are discussed. These are the lesions of granuloma annulare, Wegener's granulomatosis, and rheumatoid vasculitis. In the subsequent half of this two-part series, the "red" collagenolytic granulomas will be discussed; these are the lesions of necrobiosis lipoidica, necrobiotic xanthogranuloma, rheumatoid nodules, Churg-Strauss syndrome, and eosinophilic cellulitis (Well's syndrome).

Expression of the histiocytic marker PG-M1 in granuloma annulare and rheumatoid nodules of the skin

BACKGROUND

The expression of PG-M1, the most specific histiocytic marker, has not yet been studied in granuloma annulare (GA) and other palisaded granulomas of the skin. We evaluated the reactivity of PG-M1 with a series of GA and rheumatoid nodules (RN) to establish the sensitivity and potential usefulness of this marker in the diagnosis and characterization of these entities.

METHODS

Histological sections from 30 GA and 15 RN were immunostained with PG-M1. For comparison, additional sections were stained with KP-1 and lysozyme. The stains were recorded as negative, weakly positive (1+) and strongly positive (2+).

RESULTS

PG-M1 stained all cases of GA (100%). KP-1 and lysozyme stained 26 (86%) and 18 (60%) GA cases, respectively. PG-M1 exhibited a significantly stronger staining intensity (1.8 +/- 0.07) when compared with KP-1 (1.4 +/- 0.13) (p = 0.018) and with lysozyme (0.9 +/- 0.15) (p < 0.0001). All RN were stained by PG-M1 (100%). KP-1 and lysozyme stained 14 (93%) and six (40%) RN cases, respectively. PG-M1 staining intensity (1.6 +/- 0.13) was slightly higher than that of KP-1 (1.4 +/- 0.18) (p = 0.27) and significantly higher than that of lysozyme (0.4 +/- 0.13) (p < 0.0001).

CONCLUSIONS

PG-M1 is consistently and strongly expressed by the histiocytic population of GA and RN, being more sensitive and reliable than other histiocytic markers. We recommend its use in difficult cases in which the histiocytic nature of the lesion needs to be confirmed.

Granuloma annulare: an immunohistochemical study

The monocyte/histiocytic response in granuloma annulare has not been extensively studied. We studied the immunohistochemical staining pattern in granuloma annulare by using a panel of markers for "histiocytic" cells including Ham 56, KP1, factor XIIIa, Mac 387, vimentin, and lysozyme. The infiltrate failed to stain with the histiocytic markers, except with antibodies against vimentin and lysozyme. Commonly used histiocytic markers for infectious, immunogenic, and foreign body granulomas fail to stain the infiltrate in granuloma annulare. We hypothesize that a locally derived, immunologically distinct population of histiocytes produces the reaction pattern of granuloma annulare.

Granuloma annulare: a rare occipital lesion in infants and children

Subcutaneous granuloma annulare is a rare scalp lesion that occurs in infants and children. Occurrence in the occipital region, absence of bone involvement, slow growth, and foci of necrosis of collagen surrounded by palisading granulomatous inflammation are characteristic of this lesion. Although the cause remains unknown, it is not infectious and is more likely due to a defect in cell-mediated immunity. The prognosis after excision is excellent. Increased awareness that this peculiar granulomatous lesion can rarely occur in the soft tissue of the occipital region will help prevent confusion with neoplastic or infectious processes.

Benign fibrous histiocytoma of the skin. An immunohistochemical analysis of 30 cases

In this study the immunohistochemical analysis of distinct morphologic variants of benign fibrous histiocytoma (BFH) of the skin was performed with immunoperoxidase technique for both lysozyme and alpha-1-antitrypsin (A1AT). Thirty cases including cellular, fibrous and xanthomatous variants of BFH were selected. Out of the total 6 cases (20%) showed positive staining only for A1AT, 3 cases (10%) only for lysozyme and 10 (33.3%) for both markers. Thus, 19 cases (63.3%) showed positive staining for one of both markers. Positive staining was higher in the cellular variant than the fibrous and xanthomatous types. Negative staining of tumors of definite histiocytic morphology may be interpreted as a variable enzymatic expression of different histiocytic activation and/or undetectable enzymatic content by the current techniques. These results are in accordance with our previous evolutional hypothesis of BFH which considered the cellular tumors as functionally more active variants evolving to less cellular, more fibrous and less active types. Current histogenetic concepts about this controversial group of skin neoplasms are discussed.

Hepatic sinusoidal macrophages in alcoholic liver disease

Lysozyme is a bacteriocidal enzyme which is a major stable secretory product of mononuclear phagocytes, including hepatic sinusoidal macrophages (HSM), and serves as a good marker for these cells. Patients with alcoholic liver disease (ALD) have decreased HSM function which is reflected in reduced clearance of microorganisms and endotoxin derived from the gut. The HSM population in 54 liver biopsies from patients with ALD was studied using immunoperoxidase staining of lysozyme and was compared with 15 histologically normal controls. In both groups lysozyme positive HSM were more numerous in periportal than perivenous parenchyma. In each zone there were significantly fewer positive HSM in cases of ALD than in controls, in alcoholic hepatitis than in ALD without hepatitis, and in cirrhosis than in ALD without cirrhosis. These findings suggest a decreased population of functionally active HSM in ALD which correlates with severity of liver damage. This might be due to decreased lysozyme content of the entire HSM population or to the existence of two populations, one positive and one negative for lysozyme. The observed decrease in HSM function explains many of the phenomena observed in ALD.

Eosinophils in the cellular infiltrate of granuloma annulare

Eosinophils have been described in the infiltrates of granuloma annulare, but their frequency, distribution and extent are not well documented. We found eosinophils in 18/45 (40%) cases of granuloma annulare, without significant variation relating to histologic sub-pattern. Eosinophils were seen in over half the cases of deep granuloma annulare and in over one-third of the cases of superficial granuloma annulare. This study demonstrates the lack of specificity of eosinophils in differentiating superficial granuloma annulare from deep granuloma annulare, granuloma annulare from necrobiosis lipoidica, and granuloma annulare from occasional clinical simulants which histologically show eosinophils, such as arthropod bite reactions.