Reactive Granulomatous Dermatitis: A Review of Palisaded Neutrophilic and Granulomatous Dermatitis, Interstitial Granulomatous Dermatitis, Interstitial Granulomatous Drug Reaction, and a Proposed Reclassification

The terms "palisaded neutrophilic and granulomatous dermatitis," "interstitial granulomatous dermatitis," and the subset "interstitial granulomatous drug reaction" are a source of confusion. There exists substantial overlap among the entities with few strict distinguishing features. We review the literature and highlight areas of distinction and overlap, and propose a streamlined diagnostic workup for patients presenting with this cutaneous reaction pattern. Because the systemic disease associations and requisite workup are similar, and the etiopathogenesis is poorly understood but likely similar among these entities, we propose the simplified unifying term "reactive granulomatous dermatitis" to encompass these entities.

Granulomatous & histiocytic dermatitides

Granulomas of the skin may be classified in several ways. They are either infectious or non-infectious in character, and they contain areas of necrobiosis or necrosis, or not. Responsible infectious agents may be mycobacterial, fungal, treponemal, or parasitic organisms, and each case of granulomatous dermatitis should be assessed histochemically for those microbes. In the non-infectious group, examples of necrobiotic or necrotizing granulomas include granuloma annulare; necrobiosis lipoidica; rheumatoid nodule; and lupus miliaris disseminates faciei. Non-necrobiotic/necrotizing and non-infectious lesions are exemplified by sarcoidosis; foreign-body reactions; Melkersson-Rosenthal syndrome; Blau syndrome; elastolytic granuloma; lichenoid and granulomatous dermatitis; interstitial granulomatous dermatitis; cutaneous involvement by Crohn disease; granulomatous rosacea; and granulomatous pigmented purpura. Histiocytic dermatitides that do not feature granuloma formation are peculiar reactions to infection, such as cutaneous malakoplakia; leishmaniasis; histoplasmosis; lepromatous leprosy; rhinoscleroma; lymphogranuloma venereum; and granuloma inguinale.

Autoimmunity-related granulomatous dermatitis in association with hepatitis

AIM

Both interstitial granulomatous dermatitis (IGD) and palisaded neutrophilic granulomatous dermatitis (PNGD) are rare disorders typically associated with systemic autoimmune conditions. They probably represent different aspects of a disease spectrum encompassing the concept of autoimmunity-related granulomatous dermatitis (ARGD).

CASE REPORT

A 61-year-old woman presented with ARGD and autoimmune hepatitis. The clinical presentation suggested PNGD, while histopathology was consistent with IGD.

DISCUSSION

The association of ARGD with autoimmune hepatitis is apparently a rare event. The present case shows that the clinicopathological correlation in ARGD does not always clearly fit with the classical presentations of IGD or PNGD.

Comparison of immunohistochemical and qPCR methods from granulomatous dermatitis lesions for detection of leishmania in dogs living in endemic areas: a preliminary study

Background

In canine leishmaniosis (CanL) endemic areas, pathologists often receive skin biopsies for testing with histopathologic findings suggestive—but not conclusive for a definitive diagnosis—of CanL lesions. I the absence of data on the infective status of animals, the diagnosis can therefore be challenging. The aim of this retrospective study was to evaluate the ability of immunohistochemistry (IHC) and quantitative PCR (qPCR) methods to detect Leishmania infection in skin biopsies with a histopathologic diagnosis of lymphoplasmacytic/histiocytic and/or granulomatous dermatitis and to correlate the pattern, depth and severity of the histopathologic lesions with the parasite load detected by qPCR and IHC.

Methods

Thirty formalin-fixed, paraffin-embedded skin samples were evaluated by hematoxylin–eosin (H&E) staining, IHC, conventional PCR (cPCR) and qPCR. The severity, pattern and depth of the dermal inflammation and parasite load were graded.

Results

Leishmania was detected by H&E staining in 8/30 sections (26.66%) and by IHC in 14/30 samples (46.66%). Parasite DNA was detected in 14/30 samples (46.66%) by cPCR and in 21/30 samples (70%) by qPCR, with an extremely variable parasite load (1.32–62.700 copies). The level of agreement was fair between H&E staining and cPCR (κ = 0.32), and moderate between H&E staining and IHC (κ = 0.58). The level of agreement between IHC and cPCR was good (κ = 0.65); between IHC and qPCR, moderate (κ = 0.41); and between cPCR and qPCR, fair (κ = 0.28). A significant association was found between the severity of dermal inflammation and the parasitic skin load by IHC, although with weak linear correlation.

Conclusions

Our study underlines the difficulty of obtaining a definitive diagnosis of CanL cutaneous lesions, even with the most accurate diagnostic tests currently available. Based on our results, no single test is suitable on its own for the diagnosis of cutaneous lesions caused by Leishmania. However, in the presence of a moderate/severe lymphoplasmacytic/histiocytic and/or granulomatous dermatitis, we suggest performing IHC, as in our study this technique proved to be the method with the highest discriminatory power to estimate the role of the parasite in skin lesions. In mild lesions, IHC loses its discriminatory power and should be effectively combined with techniques such as qPCR.

Graphical Abstract

Cutaneous infection with Mycobacterium obuense

This report describes the presence of cutaneous nodules and ulceration of the right leg of 1-year duration in an elderly woman. Prior biopsies had demonstrated dermal and subcutaneous granulomatous inflammation. Special stains for microorganisms and cultures were repeatedly negative. Polymerase chain reaction evaluation of the tissue block demonstrated the presence of Mycobacterium obuense.

Truncal necrobiosis lipoidica diabeticorum: A first case report

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Necrobiosis lipoidica is a rare chronic dermatitis found in diabetic patients.

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These skin lesions affect 0.3–1.2% of patients with diabetes mellitus.

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Our patient developed necrobiosis lipoidica on the trunk, an unusual location.

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Treatment of necrobiosis lipoidica is difficult, related to good glycemic control.

Introduction

Necrobiosis lipoidica (NL) is a known chronic rare granulomatous dermatitis. NL typically occurs in the lower extremity, there have only been previously reported cases of NL on the face, scalp, forearms, and dorsum of the hands. However, truncal NL is not a typical location.

Presentation of case

A 67-year-old man known to have diabetes type 2, presented with a 3-year history of painful and itchy skin lesions on the right lateral chest wall. On clinical examination, he had a red discolored patch with superficial capillaries and yellow discoloration at the center. Based on the histological examination, necrobiosis lipoidica was confirmed. Initial treatment with clobetasol propionate, tacrolimus, and topical corticosteroid cream was unsuccessful, and further NL lesions developed on the lower limb.

Discussion

NL rash is characterized by its location in the lower limbs and rarely involves fingers, hands, scalp, or face. It is noteworthy that the patient presented with NL skin lesions bon the trunk, which is outside the usual presentation. The prevalence of NL ranges from 0.3% to 1.2% among patients with diabetes mellitus. The treatment of NL is usually difficult. Initial management includes smoking cessation and proper diabetes control. In addition, intralesional and topical corticosteroids might be effective. In this case report, there was no improvement in NL despite the use of topical corticosteroids.

Conclusion

Immediate diagnosis and treatment of NL may prevent disease progression; therefore, the diagnosis of NL should be considered, even in an unusual location.

A report of disseminated actinic granuloma: An unusually extensive presentation

In this report, a case of disseminated actinic granuloma in a 50-year-old female with type 2 diabetes mellitus is described. This case is unique due to the unusually extensive cutaneous involvement of the face, neck, trunk, and extremities at initial presentation. The lesions were in a striking photo-distribution, highlighting ultraviolet light as an important environmental trigger for this process. Interestingly, the patient refused the recommended systemic therapy with hydroxychloroquine, despite her significant burden of skin disease. This refusal stems from an unexpected reluctance on the part of the patient to take this medication due to the publicity and media coverage of side effects associated with inappropriate prescribing of this drug during the COVID-19 pandemic, presenting a new and surprising treatment barrier that clinicians may need to overcome.

Non-Infectious Granulomatous Dermatoses: A Pathologist's Perspective

Granulomatous dermatitis (GD) is one of the commonest tissue reaction patterns encountered in dermatopathology practice. Granulomatous inflammation in the skin can be seen in a wide range of conditions, thus, granulomatous dermatitis always poses significant challenge even to the astute dermatologists and dermatopathologists. Broadly, granulomatous dermatitis is divided into two groups-infectious and non-infectious, the prevalence of both highly variable and show overlapping pathology. However, there are subtle histological clues, which when combined with clinical features, help to narrow down the differential diagnosis. Thus, a good Clinicopathological correlation (CPC) along with histochemical stains, culture and ancillary techniques including molecular studies are required for arriving at a definite diagnosis. In this review, we shall discuss the histological clues to diagnose non-infectious granulomatous dermatitis (NIGD) and their differential diagnoses.