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Cutaneous granulomatous reactions are diverse, both from the clinical and the pathological perspective. Most underlying pathophysiological aspects remain elusive. Interstitial granulomatous dermatitis and palisaded neutrophilic and granulomatous dermatitis have been claimed to be reactions to systemic disorders, such as infectious, inflammatory, or neoplastic conditions. Recently, the overarching term "reactive granulomatous dermatitis" has been coined to unify both entities. We herein report two cases of reactive granulomatous dermatitis presenting with the widely known, albeit infrequent "rope sign" and provide clinicopathological correlation. The two patients included a 53-year-old woman with enlarging erythematous plaques and underlying palpable cords on both sides of trunk near axillae (rope sign), and a 51-year-old woman with personal history of rheumatoid arthritis and a palpable cord on the left aspect of the trunk. Pathological findings were compatible with reactive granulomatous dermatitis in both cases. In conclusion, the rope sign represents a strikingly infrequent but decisive diagnostic clue of reactive granulomatous dermatitis.

Superficial granulomatous pyoderma gangrenosum is a rare, superficial, vegetating form of pyoderma gangrenosum that tends to occur as a single lesion, most commonly on the trunk. Herein, we report a clinically confounding case of disseminated superficial granulomatous pyoderma gangrenosum in a patient with a 5-year history of painful and chronic ulcerations of the bilateral upper extremities and face in a sun exposed distribution. This was a diagnostically challenging case due to the treatment-refractory nature of our patient's skin lesions and the atypical clinical and histologic presentations encountered. We review our clinical decision process and acknowledge other entities that were considered during the clinical course of this case. Additionally, we discuss the lack of responsiveness to various treatment options with eventual successful clearance of this patient's active skin disease with initiation of adalimumab.

Traditionally, skin involvement in chronic myelomonocytic leukemia (CMML) has been considered to be either specific (leukemia cutis) or non‐specific, with granulomatous dermatitis included in the latter group. More recently, the true nature of the myeloid cells present in the cutaneous infiltrates of this theoretically reactive dermatitis is being clarified with the use of new molecular techniques such as next‐generation sequencing. The same mutations in bone marrow (BM) myeloid neoplastic cells and in the cells of cutaneous infiltrates have been found. We present the case of a 77‐year‐old man who presented with spread and treatment‐resistant skin granulomatous lesions previous to the diagnosis of CMML. The same clonal mutations in SRSF2, IDH1, and RUNX1 were found in both skin and BM with resolution of the lesions after the initiation of azacytidine. In conclusion, we report an exceptional case in which specific granulomatous cutaneous lesions have preceded and allowed the earlier diagnosis of an underlying CMML and a review of all previous similar cases in the literature, including molecular alterations. [ABSTRACT FROM AUTHOR]

The pandemic of SARS-CoV-2 during the first years of the 2020s led to a great commitment to develop effective vaccines. Despite the good safety and tolerability profile, vaccines may trigger a broad spectrum of cutaneous side effects. Granulomatous dermatitis has been rarely reported after SARS-CoV-2 mRNA vaccines, but no cases of annular elastolytic giant cell granuloma have been described. Moreover, in our case, it was also associated with a central area of mid-dermal elastolysis, confirming the strong association between these two diseases already reported in the literature. The observation of occasional eosinophils within the infiltrate and the presentation of the cutaneous eruption a few days after the administration of the second dose of the Pfizer/BioNTech (BNT162b2) vaccine are highly suggestive of a drug-related eruption. To our knowledge, this is the first report in the literature of an annular elastolytic giant cell granuloma as an adverse effect of the SARS-CoV-2 vaccination. [ABSTRACT FROM AUTHOR]

This document is a case report discussing a rare adverse event associated with the use of dupilumab, a medication used to treat inflammatory skin conditions. The report includes a case study of a 64-year-old female patient who developed interstitial granulomatous dermatitis after six months of treatment with dupilumab. The article also mentions other reported cases of similar reactions and discusses potential mechanisms for these reactions. The authors emphasize the importance of recognizing and diagnosing these adverse events and providing appropriate management. [Extracted from the article]

Objective: Granulomatous dermatitis (GD) is a group of diseases grouped under two main headings: infectious and non-infectious, characterized histopathologically by granulomas and may also present with systemic findings. Granulomatous inflammation may be limited to the skin only or may occur as a symptom of a systemic disease. Material and Methods: 105 patients included who were clinically and histopathologically diagnosed with non-infectious GD in our clinic between 2006 and 2023. Results: Of the 105 patients included in our study, 79 were female and 26 were male. The mean age of the patients was 45.72 (age range 2-77). While 12 of the patients were under the age of 18, 12 patients were over the age of 65. The diagnosis of the patients were granuloma annulare (n=43), followed by sarcoidosis (n=24), necrobiosis lipoidica (n=12), interstitial GD (n=6), granulomatous rosacea (n=5), panniculitis (n=5), granuloma fasciale (n=2), Crohn’s disease (n=2), granulomatous vasculitis (n=2), piyoderma gangrenozum (n=1), post herpetic GD (n=1), lupus miliaris disseminatus faciei (n=1), granulomatous mycosis fungoides (n=1) and elastolytic giant cell granuloma (n=1). Conclusion: GDs are a heterogeneous group of diseases with varying clinical and histopathological findings. Histopathological morphology alone is rarely specific and is not sufficient to make a definitive diagnosis of the disease that plays a role in etiology. Conclusion: Differential diagnosis of GDs should be made in the light of histopathological findings, microbiological examination and clinical data. [ABSTRACT FROM AUTHOR]

Mycobacterium indicus pranii (MIP) vaccine is widely used in dermatology as immunotherapy for warts as well as in patients with leprosy. During the COVID-19 pandemic, a positive role of MIP as an immunomodulator in SARS-CoV-2 disease was reported after pilot research, with minor adverse effects. We report a case of a 65-year-old male, presenting with skin lesions suggestive of noninfective granulomatous dermatitis for 4 months, at the sites of MIP intradermal injections, allegedly received during a hospital stay for severe COVID-19 disease. The patient presented with nonhealing nodulo-ulcerative lesions at the sites of injection, which persisted for 4 months associated with intermittent serous discharge and showed no signs of healing despite supportive treatment. The patient was started on a combination therapy of ofloxacin 400mg/day and clarithromycin 500mg 12 hourly for 2 months. At the end of 2 months, all the lesions showed complete healing with a resolution of discharge and nodularity, leaving behind postinflammatory hypopigmentation and atrophic scarring. The patient was followed up for 4 months after stopping treatment during which time he had no relapse of the lesions. This case has been reported to the India Pharmacopoeia. [ABSTRACT FROM AUTHOR]

Key Clinical Message: There is a need to pay more attention to cutaneous leishmaniasis in endemic regions which may mimic other dermatoses and treatment should be initiated with a strong clinical suspicion even without any histopathologic or PCR confirmation to avoid disfigurement or development of secondary malignancy. Leishmaniasis is a vector‐borne disease with a variety of Clinical manifestations. Cutaneous leishmaniasis (CL) is the most common form of disease and can mimic other dermatoses. We describe two unusual cases of chronic leishmaniasis that remained undiagnosed for many years and led to superimposition of squamous cell carcinoma (SCC) on lesions of one patient. These reports showed that the leishmaniasis should be borne in mind by clinicians when encountering any infiltrated lesion in patients from endemic regions and treatment should be initiated with a strong clinical suspicion even without any histopathologic or PCR confirmation to avoid disfigurement or development of secondary malignancy. [ABSTRACT FROM AUTHOR]

Immune-related adverse events (irAEs) are common in patients receiving immune checkpoint inhibitors for metastatic melanoma and other advanced malignancies. Cutaneous, gastrointestinal, and endocrine (thyroid) irAEs are most prevalent, whereas neurologic irAEs are rare. We present a 73-year-old man with dementia and metastatic melanoma who developed immunotherapy-associated encephalitis and subsequently, interstitial granulomatous dermatitis with nivolumab/ipilimumab. High-dose corticosteroids successfully treated both conditions, though he never regained his baseline mental status. We review the literature on interstitial granulomatous dermatitis and encephalitis with immunotherapy.

Perforating dermatoses are dermatologic disorders with transepidermal elimination (TE) of dermal substances. While TE is typically associated with collagen and elastin, it can also occur as a secondary event in other processes, and it is important to keep a broad differential. We present a case of perforating tophaceous gout, which underscores the need for a thoughtful approach to perforating disorders. An updated review of recent literature is also presented.

Background: To date, fewer than 20 patients have been identified as having germline biallelic mutations in the coronin-1A gene (CORO1A) and its protein with clinical features of combined immunodeficiency characterized by T-cell lymphopenia ranging from the severe phenotype to the mild phenotype, recurrent infections, and lymphoproliferative disorders. However, the effects of CORO1A protein disruption on actin-dependent functions in primary cells have not been fully delineated. Objective: We sought to characterize the underlying defects of actin-dependent cellular functions in a female patient with combined immunodeficiency caused by a novel missense variant in the CORO1A gene in combination with a de novo heterozygous microdeletion of chromosome 16p11.2 and also to provide evidence of the pathogenicity of this gene mutation. Methods: To identify the genetic defect, next-generation sequencing followed by Sanger confirmation and array comparative genomic hybridization were performed. Western blot and quantitative PCR tests were used to assess the effects on the protein. Flow cytometry and live microscopy were performed to investigate cellular motility and immune cell counts and function. Results: We demonstrated that the CORO1A hemizygous variant c.19C>T, p. A7C induces significant decreases in cellular levels of the CORO1A protein while leaving mRNA concentrations unaffected. The observed mutation resulted in impaired natural killer cell cytotoxicity and platelet calcium signaling. In addition, primary granulocytes and mesenchymal cells showed significant defects in motility. Conclusion: Collectively, we added new data about the CORO1A gene as a key player in actin cytoskeleton dynamics and cell signaling. Our findings expand the clinical spectrum regarding CORO1A protein deficiency and confirm the importance of a personalized therapeutic approach for each patient.

Key Clinical Message There is a need to pay more attention to cutaneous leishmaniasis in endemic regions which may mimic other dermatoses and treatment should be initiated with a strong clinical suspicion even without any histopathologic or PCR confirmation to avoid disfigurement or development of secondary malignancy. Abstract Leishmaniasis is a vector‐borne disease with a variety of Clinical manifestations. Cutaneous leishmaniasis (CL) is the most common form of disease and can mimic other dermatoses. We describe two unusual cases of chronic leishmaniasis that remained undiagnosed for many years and led to superimposition of squamous cell carcinoma (SCC) on lesions of one patient. These reports showed that the leishmaniasis should be borne in mind by clinicians when encountering any infiltrated lesion in patients from endemic regions and treatment should be initiated with a strong clinical suspicion even without any histopathologic or PCR confirmation to avoid disfigurement or development of secondary malignancy.

Perforating dermatoses are dermatologic disorders with transepidermal elimination (TE) of dermal substances. While TE is typically associated with collagen and elastin, it can also occur as a secondary event in other processes, and it is important to keep a broad differential. We present a case of perforating tophaceous gout, which underscores the need for a thoughtful approach to perforating disorders. An updated review of recent literature is also presented. [ABSTRACT FROM AUTHOR]

Granuloma annulare is a non-infectious granulomatous skin condition with multiple different associations. We present a case of a man in his 60s with a three-week history of progressive targetoid plaques on his arms, legs, and trunk. Skin biopsy demonstrated interstitial granuloma annulare. Additional testing revealed IgM antibodies to Borrelia burgdorferi on western blot suggesting interstitial granuloma annulare was precipitated by the recent infection. Lyme disease is an uncommonly reported association with interstitial granuloma annulare.

Reactive granulomatous dermatitis (RGD) is a rare dermatosis with a variety of cutaneous manifestations unified by a dermal granulomatous infiltrate on histology. Rheumatoid arthritis and autoimmune disease are classic associations, but an increasing number of cases have been attributed to covert malignancy. Only 41 cases of paraneoplastic RGD have been documented to our knowledge and we present an additional case that manifested eight months prior to the diagnosis of ovarian cancer and clinically mimicked morphea. Histopathologic examination identifying palisaded CD68+ cells and collagen degeneration are helpful in diagnosing this entity which may mimic a host of other cutaneous processes, including metastatic disease. Cancer-directed therapies have been successful in clearing paraneoplastic RGD with or without the addition of corticosteroids, as RGD severity may be driven by the underlying malignancy. This case highlights the importance of utilizing histopathology to confirm the diagnosis given its nonspecific clinical findings, as well as the importance of considering malignancy and metastatic disease in patients diagnosed with RGD regardless of their cancer history.

The pandemic of SARS-CoV-2 during the first years of the 2020s led to a great commitment to develop effective vaccines. Despite of the good safety and tolerability profile, vaccines may trigger a broad spectrum of cutaneous side effects. Granulomatous dermatitis has been rarely reported after SARS-CoV-2 mRNA vaccines, but no cases of annular elastolytic giant cell granuloma have been already described. Moreover, in our case, it was also associated with a central area of mid-dermal elastolysis, confirming the strong association between these two diseases already reported in literature. The observation of occasional eosinophils within the infiltrate and the presentation of the cutaneous eruption few days after the administration of the second dose of Pfizer/BioNTech (BNT162b2) vaccine are highly suggestive of a drug-related eruption. To our knowledge, this is the first report in literature of an annular elastolytic giant cell granuloma as an adverse effect of SARS-CoV-2 vaccination.

A dog and a cat presented with pyogranulomatous mycotic pododermatitis. Panfungal PCR and next‐generation sequencing identified Paraconiothyrium cyclothyrioides with 100% identity. Paraconiothyrium cyclothyrioides can rarely cause cutaneous infection and systemic disease in immunocompromised humans. This is the first report of infections in domestic animal species. [ABSTRACT FROM AUTHOR]

We report a patient with new-onset ulcerated granuloma annulare with concomitant involvement of B-cell leukemia. A granuloma annulare-like eruption with concomitant B cell chronic lymphocytic leukemia involvement in the skin is extremely rare, as only three cases have been previously reported in the literature to our knowledge. Given the rarity of ulceration in conventional granuloma annulare, it is possible this finding may serve as a diagnostic clue for underlying malignancy.

Blau syndrome is a rare auto-inflammatory disease caused by NOD2 mutation and a persistent hyper-inflammatory reaction mediated by transcription factor (NF-κB). The disease is characterized by an early onset of age and non-casein-like granulomatous inflammatory responses. The typical clinical manifestations are granulomatous dermatitis, symmetric arthritis, and uveitis. At present, the treatment of Blau syndrome is mainly based on glucocorticoid and immuno-suppressants, but the therapeutic effect is still not satisfactory.

Background: Extranodal NK/T cell lymphoma, nasal type (ENK/T) with cutaneous involvement has various histopathological findings and diverse clinical manifestations. Methods: A retrospective study of cutaneous involvement of ENK/T lymphoma between 2006 and 2018 was conducted. Results: Twenty-two cases were eligible for this study. Twelve cases could be proven as secondary cutaneous involvement by ENK/T lymphoma, while the remaining could not be confirmed as primary cutaneous ENK/T lymphoma. The histopathological patterns included dermal and subcutaneous nodular infiltration pattern in 11/22 cases (50%), lobular panniculitis pattern in 6/22 cases (27.3%), interface dermatitis pattern in 4/22 cases (18.2%), and granulomatous dermatitis pattern in 1/22 case (4.5%). The median follow-up was 18.3 months. Overall, the one-year and five-year survival rates were 31.3% and 13.3%, respectively. Conclusions: A variety of histopathological patterns of cutaneous involvement by ENK/T lymphoma should be differentiated from other cutaneous lymphomas, dermatitis, and infection. When atypical medium or large-sized lymphoid cells are encountered within skin lesions, pathologists should realize these lesions can be ENK/T lymphoma, especially in cases with coexisting tumor necrosis or angioinvasion. A complete evaluation of the upper aerodigestive tract is mandatory to identify the occult primary site of ENK/T lymphoma before establishing primary cutaneous ENK/T lymphoma.

Introduction: Reactive granulomatous dermatitis (RGD) is a new entity, which is highly associated with systemic disorders. There is scarce data regarding interstitial granulomatous dermatitis (IGD) and palisaded neutrophilic granulomatous dermatitis (PNGD). Objectives: We aimed to evaluate clinical and histopathological characteristics of IGD and PNGD as unified entities under the term of RGD. Methods: Observational, retrospective, single-center study of patients diagnosed with IGD and PNGD between 2012 and 2021 were included in the study. Results: Of 16 patients with RGD 13 had IGD and 3 had PNGD (14 females, 2 males) with a mean age of 62,5. The most common presentation was plaques 37,5% (n=6), followed by patches 25%. The most common localization of involvement was lower extremity 75%, followed by trunk and upper extremity. Multiple localization of involvement was determined in 75% of patients. None of the patients had rope sign. Associated comorbidities such as autoimmune diseases and malignancies were detected in 68,7% of patients. In majority of biopsies (85,7%), there were lymphohistiocytic cell infiltration. Other accompanying cells were scarce neutrophils 31,2% and eosinophils 31,2%. All of the biopsies had interstitially located lymphohistiocytic cell infiltration surrounding with swollen and degenerated collagen. Palisaded pattern was determined in 18,7% of patients and floating sign was seen in 18,7% of biopsies. Conclusions: RGD is a rare entity and most patients with RGD had associated disorders such as autoimmunity or malignancy. There is overlapping between IGD and PNGD, therefore supporting the usage of umbrella term as reactive granulomatous dermatitis is compatible with the literature.

Necrobiosis lipoidica is a chronic granulomatous disease of unknown etiopathogenesis, which is often difficult to treat. While data from randomized controlled trials for the treatment of necrobiosis lipoidica is lacking, several treatments of varying efficacy for necrobiosis lipoidica have been reported in the scientific literature. We present a case of a 29-year-old female with uncontrolled diabetes and treatment-resistant necrobiosis lipoidica which was responsive to ustekinumab.

Leishmania infantum is the causal agent of cutaneous and visceral canine leishmaniasis, a disease widely described in Europe and Latin America. This study describes a case of a canine Canary mastiff breed, born in Mexico that was referred to consult by an alopecic lesion and generalized lymph adenomegaly. Diagnosis of leishmaniasis was established by impression smears of the lesion that showed amastigotes within macrophages. Due to the poor body condition of the animal, euthanasia and necropsy were conducted and samples taken from skin, lymph nodes, liver, kidney, and spleen to perform histological and molecular analysis. In skin, spleen and kidney granulomatous lesions were observed showing amastigotes of Leishmania. The diagnosis of L. infantum was confirmed by using molecular tools. The report of this case suggests the potential risk of this disease in a non-endemic region from Mexico. [ABSTRACT FROM AUTHOR]

Abstract 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

A 55-year-old man presented with a history of asymptomatic, bilateral, figurate dermatosis consisting of erythematous, annular, linear, andarciform, indurated nodules and plaques on the lateral walls of thorax, flanks, and hypogastrium. His medical history was positive for chronic hepatitis C. Skin biopsy was compatible with the diagnosisof interstitial granulomatous dermatitis. Additionalinvestigation revealed positive rheumatoid factor, antinuclear antibodies, and cryoglobulins. Thepatient started treatment with high-potency topical corticosteroid. After 12 weeks of treatment there was a partial clinical improvement of thedermatosis. Interstitial granulomatous dermatitis exhibits a distinct histopathological pattern with a diverse clinical appearance, which can be associated with autoimmune systemic diseases, neoplasms, several drugs, and infections. Optimal therapy for this condition is yet to be established, but topical corticosteroids have been a mainstay of treatment.

Background: Extranodal NK/T cell lymphoma, nasal type (ENK/T) with cutaneous involvement has various histopathological findings and diverse clinical manifestations. Methods: A retrospective study of cutaneous involvement of ENK/T lymphoma between 2006 and 2018 was conducted. Results: Twenty-two cases were eligible for this study. Twelve cases could be proven as secondary cutaneous involvement by ENK/T lymphoma, while the remaining could not be confirmed as primary cutaneous ENK/T lymphoma. The histopathological patterns included dermal and subcutaneous nodular infiltration pattern in 11/22 cases (50%), lobular panniculitis pattern in 6/22 cases (27.3%), interface dermatitis pattern in 4/22 cases (18.2%), and granulomatous dermatitis pattern in 1/22 case (4.5%). The median follow-up was 18.3 months. Overall, the one-year and five-year survival rates were 31.3% and 13.3%, respectively. Conclusions: A variety of histopathological patterns of cutaneous involvement by ENK/T lymphoma should be differentiated from other cutaneous lymphomas, dermatitis, and infection. When atypical medium or large-sized lymphoid cells are encountered within skin lesions, pathologists should realize these lesions can be ENK/T lymphoma, especially in cases with coexisting tumor necrosis or angioinvasion. A complete evaluation of the upper aerodigestive tract is mandatory to identify the occult primary site of ENK/T lymphoma before establishing primary cutaneous ENK/T lymphoma. [ABSTRACT FROM AUTHOR]

Blau Syndrome (BS) is a rare autoinflammatory granulomatous disorder which mostly develops at an early age (less than four years) and is described by granulomatous dermatitis, symmetric arthritis and recurrent uveitis. Hereby, the authors present a case of a 5-year-old female child with joint pain and swelling since four years. Initially, her diagnosis was made as juvenile idiopathic arthritis-polyarticular Rheumatoid Factor (RF) negative and was initiated on methotrexate along with bridge steroids (prednisolone). When she presented to the hospital, she had skin coloured micropapular rashes, mostly non follicular over body, from last nine months and after skin and synovial biopsy, the diagnosis was reviewed as early onset sarcoidosis/BS-sporadic type. The present rare report highlights that, BS is an under-recognised and reported childhood arthritis which may have multisystem involvement. The onset of arthritis without ocular or skin manifestations may be mistaken as juvenile idiopathic arthritis.

Soil and freshwater-dwelling amoebae may opportunistically infect the skin and evoke a granulomatous dermatitis that camouflages their underlying morphology. Amoebic infestations are incredibly rare in the U.S., predominantly occurring in the young, elderly, and immunocompromised. Sadly, because diagnosis is difficult and unsuspected, most cases are diagnosed at autopsy. The following case is of a healthy 84-year-old man with a non-healing nodulo-ulcerative cutaneous lesion on his left forearm that appeared following a gardening injury. Lesional punch biopsies repeatedly showed non-specific granulomatous inflammation with no pathogens evident histologically or by culture. Histopathologic diagnosis was made five months after initial presentation via identification of amoebic trophozoite forms in tissue from a large excisional specimen. Anti-amoebic therapy was initiated immediately. The patient experienced mental status changes three days following lesion excision, with evidence of a cystic mass in the left medial parieto-occipital lobe by CT. Both intraoperative brain biopsies and cutaneous tissue samples tested positive for Balamuthia mandrillaris by indirect immunofluorescent antibody assay performed at the Centers for Disease Control. The patient achieved a full recovery on a triple antibiotic regimen. Clinical suspicion and thorough histopathologic analysis may determine the difference between survival and death for a patient presenting with a treatment-refractory localized granulomatous lesion.

We present a 42-year-old woman with no history of diabetes or glucose intolerance who had a 5-year history of ulcerative necrobiosis lipoidica (NL). Despite failure of multiple medications, she experienced clearing of her ulcers after her treatment was changed to ustekinumab. We discuss our patient’s disease course and elaborate upon mechanistic reasons for her improvement related to ustekinumab therapy.

Necrobiosis lipoidica is a rare chronic granulomatous disease that has historically been associated with diabetes mellitus, but recently it is thought to be secondary to microangiopathic changes. We report a necrobiosis lipoidica case of a five-year-old girl with diabetes since the age of two, because it is exceptionally unusual in pediatric diabetes. Necrobiosis lipoidica should be considered in pediatric patients with slowly expanded erythematous plaques and patches. This will help protect the patient from other important diabetic microangiopathic complications, such as nepropathy and retinopathy and also malignant progression, such as squamous cell carcinoma.

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. [ABSTRACT FROM AUTHOR]

Introduction: Granulomatous dermatitis has a varied differential diagnosis ranging from infectious etiology to immune mediated diseases. In tropical countries like India, infectious etiology forms an important cause of granulomatous dermatitis with tuberculosis (TB) and leprosy being the major contributing factors. The present study was carried out with the aim to determine the frequency of various etiological agents causing infectious granulomatous dermatitis in our hospital setup and to see clinicohistopathological correlation in these cases. Materials and Methods: This is a hospital based retrospective study conducted in the department of pathology over a period of 1 year. All the skin biopsy cases diagnosed as infectious granulomatous dermatitis were retrieved from the histopathology record section for analysis and were categorized based on the causative etiological agents. Special stains were applied wherever necessary in addition to routine hematoxylin and eosin stain. Results: A total of 40 cases of infectious granulomatous dermatitis were included in the present study. Most common diagnosis was leprosy (57.5%), followed by TB (30.0%), actinomycosis (5.0%), dermatophytosis (2.5%), histoplasmosis (2.5%), and cysticercosis (2.5%). Gender wise distribution showed male predominance with 57.5% of cases and age wise distribution showed a peak in the age group of 41–60 years (32.5%). Clinicohistopathological correlation was found in 87.50% of the cases. The unusual clinical presentations were seen in cases of cysticercosis, actinomycosis, and histoplasmosis. Conclusion: Histopathological examination of the skin biopsies is an important diagnostic tool providing definitive diagnosis as well as clinicohistopathological correlation in cases of infectious granulomatous dermatitis.

Abstract is missing (Quiz)

Blau Syndrome (BS) is a rare autoinflammatory granulomatous disorder which mostly develops at an early age (less than four years) and is described by granulomatous dermatitis, symmetric arthritis and recurrent uveitis. Hereby, the authors present a case of a 5-year-old female child with joint pain and swelling since four years. Initially, her diagnosis was made as juvenile idiopathic arthritis-polyarticular Rheumatoid Factor (RF) negative and was initiated on methotrexate along with bridge steroids (prednisolone). When she presented to the hospital, she had skin coloured micropapular rashes, mostly non follicular over body, from last nine months and after skin and synovial biopsy, the diagnosis was reviewed as early onset sarcoidosis/BS-sporadic type. The present rare report highlights that, BS is an under-recognised and reported childhood arthritis which may have multisystem involvement. The onset of arthritis without ocular or skin manifestations may be mistaken as juvenile idiopathic arthritis. [ABSTRACT FROM AUTHOR]

Palisading granulomatous dermatitis and panniculitis is recognized in various cutaneous inflammatory lesions secondary to presumed collagen damage. Cutaneous nodules with a palisading arrangement of histiocytes surrounding foci of collagen degeneration have been clinically termed palisading granuloma in dogs. Study aims were to characterize the cellular infiltrate of canine palisading granuloma and document salient clinical features. Inclusion criteria were met for 36 dogs and encompassed nodular dermal and subcutaneous histiocyte-predominant cellular infiltrates targeting and enveloping collagen fibers/necrotic foci with palisading configurations. Infectious causes were ruled out via standard histochemical stains and/or clinical data. Medical records were reviewed for signalment, clinical features, treatment, outcome, and comorbidities. Immunohistochemistry (IBA1, CD204, E-cadherin) and Masson's trichrome stain were used to assess histiocytic populations and dermal collagen, respectively. The histiocytes had moderate or strong immunolabeling for IBA1 and CD204 in 36/36 dogs (100%) and mild positive immunolabeling for E-cadherin in 3/36 dogs (8%). Alteration of collagen was graded as moderate or strong in 32/36 dogs (89%) and mild in 3/36 dogs (8%). Large breeds predominated with 30/36 dogs (83%) being ≥23 kg. Focal nodules were identified in 31/36 dogs (86%). The head/face were involved in 19/36 dogs (53%) and the extremities in 18/36 dogs (50%). Lesions from the 5/36 dogs (14%) with multiple nodules contained prominent eosinophilic infiltrates. Following excision, there was no evidence of recurrence. In conclusion, palisading granulomas are a distinct, non-neoplastic, histiocyte-predominant inflammatory condition in dogs associated with altered dermal collagen and favorable prognosis. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Blau syndrome is a rare condition characterized by the triad of granulomatous skin lesions, symmetric polyarthritis with boggy joint swellings, and ocular inflammation. It has an autosomal dominant mode of inheritance and occurs due to a mutation in CARD-15/NOD-2 gene which encodes the cytosolic NOD2 protein, a key molecule in the regulation of innate immunity. Clinical onset is generally in the 1st year of life and is characterized by articular, cutaneous, and ocular noncaseating granulomatous inflammation, which can be variably associated with a heterogeneous systemic spectrum. Here, we describe one such rare case.

Necrobiosis lipoidica is a rare chronic granulomatous disease that has historically been associated with diabetes mellitus, but recently it is thought to be secondary to microangiopathic changes. We report a necrobiosis lipoidica case of a five-year-old girl with diabetes since the age of two, because it is exceptionally unusual in pediatric diabetes. Necrobiosis lipoidica should be considered in pediatric patients with slowly expanded erythematous plaques and patches. This will help protect the patient from other important diabetic microangiopathic complications, such as nepropathy and retinopathy and also malignant progression, such as squamous cell carcinoma. [ABSTRACT FROM AUTHOR]

Oncolytic viruses represent a novel drug class in which native or modified viruses mediate tumor regression through selective replication within and lysis of tumor cells as well as induction of systemic antitumor immunity capable of eradicating tumor at distant, uninjected sites. Talimogene laherparepvec (TVEC) is a type I herpes simplex virus genetically modified to preferentially replicate in tumor cells, enhance antigen loading of MHC class I molecules and express granulocyte-macrophage colony-stimulating factor to increase tumor-antigen presentation by dendritic cells. It is presently the only oncolytic virus approved by the FDA with an indication for advanced melanoma based upon improved durable response rate in a randomized, phase III trial. Clinical trials are underway in melanoma investigating TVEC as neoadjuvant monotherapy and in combination with checkpoint inhibitors for unresectable disease as well as in an array of other malignancies. It is appropriate to review TVEC's biology mechanism of action, clinical indication and future directions as a prototype of the burgeoning class of oncolytic viruses.

Granulomatous dermatitis following the administration of various vaccines has previously been reported. However, cases of cutaneous granulomatosis following the measles, mumps, and rubella (MMR) vaccine have not yet been reported. We report the case of a 3‐year‐old boy with a granuloma annulare‐like reaction following MMR vaccination. [ABSTRACT FROM AUTHOR]

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.