Granulomatous inflammation is a specialized type of chronic inflammatory reaction consisting of focal localization with aggregates of epithelioid macrophages, multiple-nucleated gigantic cells, and lymphocytes. It is a chronic response to a broad spectrum of infectious and non-infectious stimuli and is also among the most common histopathological observations in dermatopathology [1]. Granulomatous response is an immunologic mechanism that contains and segregates an antigenic trigger, which, if allowed to persist, is resistant to normal enzymatic degradation [2]. These lesions can present themselves clinically in the form of papules, nodules, plaques, or ulcers and resemble several dermatological diseases, which present a diagnostic dilemma. [3]. The etiological factors for granulomatous skin lesions depend on the geographical location, environmental factors, and socioeconomic conditions. In tropical countries and less developed nations, the primary cause of such lesions includes leprosy, cutaneous tuberculosis, and deep fungal infections [4, 5]. In developed countries, there is a predominance of non-infectious causes for granulomatous skin lesions, which include sarcoidosis, foreign-body reactions, necrobiotic granulomas, and granuloma annulare [6]. The Mycobacterium leprae and Mycobacterium tuberculosis continue to be major organisms that cause infection, and the diagnosis is achieved by the selected clinicopathological correlation and is aided with special stains (Ziehl-Neelsen and Fite-Faraco stains) [7]. Histopathology is an indispensable method for the diagnosis and classification of granulomatous lesions. The important histological subtypes are tuberculoid, sarcoidal, necrobiotic, suppurative, and foreign-body granulomas, each with a characteristic cellular composition and distributional pattern [8]. Nevertheless, there is a great amount of overlap between the various categories; therefore, histopathological analysis should not be done without applying it to clinical information and microbiological results [9]. The diagnostic accuracy is further advanced by special stains, culture, and polymerase chain reaction (PCR) techniques, which are used to determine a particular etiological agent [10]. A number of studies across India and other countries have pointed to the prevalence of leprosy and cutaneous tuberculosis within granulomatous dermatoses in the endemic areas [4, 5, 11]. Few studies have reported Leprosy to make more than 70% of the granulomatous skin lesions, followed by cutaneous tuberculosis and fungal infections [12]. Non-infectious granulomatous infections like sarcoidosis, granuloma annulare, and necrobiotic xanthogranuloma are relatively uncommon but clinically important as they appear commonly in cases with systemic diseases [6, 13]. Clinicopathological approach still plays an important role in the discrimination of these entities. Misdiagnosis or late identification may result in inappropriate therapy, particularly in infectious granulomatous dermatoses in which treatment at an early stage prevents the spread of the infection and complications [7, 9]. Moreover, the tendency of granulomatous skin disease within a particular population indicates the existing population health and socioeconomic factors of hygiene, immunization, and access to healthcare institutions [11]. With this background, we in the current study tried to evaluate the clinic-histopathological pattern of granulomatous skin infections with emphasis on the prevalence, morphology, and etiological spectrum. These kinds of studies provide evidence for improved diagnostic precision and treatment decision-making.

This prospective study was conducted in the Department of Pathology with specimens received from the Department of Dermatology at Mahavir Institute of Medical Sciences, Vikarabad, Telangana. Institutional Ethical approval was obtained for the study. Written consent was obtained from all the cases included in the study after explaining the nature of the study and possible outcomes in the vernacular language. The sampling method was based on convenience sampling with the availability of cases and institutional resources. Inclusion criteria 1. Patients presenting with cutaneous lesions clinically suspected to be granuloma 2. Cases in which a diagnostic skin biopsy was required 3. Patients of all age groups 4. Males and Females 5. Those willing to sign informed consent Exclusion criteria 1. Patients on specific antimicrobial therapy for lesions 2. Patients currently on corticosteroids or immunosuppressive therapy 3. Patients with bleeding disorders 4. Poor general condition of patients, where biopsy was not feasible 5. Those cases that did not sign informed consent Sample size calculation: sample size was calculated with a smaller prevalence estimate (p = 0.5) to maximize a sample size with a 95% confidence interval (Z = 1.96) and a tolerable margin of error (d) of 13%. N=Z2 x p (1-p)/d2 = (1.962 x 0.5 x 0.5)/ (0.13)2 = 57, rounded to 60 in case of any exclusions. The sample was taken consecutively (non-probability) until the target sample was reached. After selection of the case based on the inclusion and exclusion criteria, a detailed demographic profile of the patient was collected in a structured proforma, which included details of age, sex, residence, and socioeconomic status. A detailed clinical history of the lesion in question was obtained, with duration, progression of the lesion, systemic symptoms, and any treatment for the same done previously. The characteristics of the lesion were gathered, which included number, location, morphology (papule/nodule/plaque/ulcer, size, and surface changes. As clinically applicable, relevant systemic examination and basic laboratory investigations were carried out. Before the biopsy, a dermatologist made a provisional clinical diagnosis. Biopsy procedure: An incisional or excisional punch biopsy (4-6 mm or both when indicated) of the representative portion of the lesion, preferably of the active edge in ulcerated lesions, was made under aseptic conditions with the use of local anesthetic (2% lignocaine). The biopsy specimen was immediately fixed in 10% neutral buffered formalin and brought to the histopathology lab for examination. Histopathology processing was done with paraffin-embedded tissue, and sections of (3–5 µm) were cut and stained with hematoxylin and eosin (H&E). As required in the cases, special stains were utilized, which included Ziehl–Neelsen (for acid-fast bacilli), Fite-Faraco (for Mycobacterium leprae), Periodic acid–Schiff (PAS), and Gomori methenamine silver (GMS) for fungal carbohydrates. The histopathological assessment of slides was done by an experienced pathologist, and two pathologists examined all the slides independently. Granuloma was categorized as (tuberculoid, sarcoidal, necrobiotic, suppurative, foreign-body, histoid, mixed) according to cellular composition, the presence/absence of caseation /necrosis, distribution, and epidermal/dermal changes. Clinicopathologic concordance was determined through the comparison of the pre-biopsy clinical diagnosis and the final histopathological diagnosis. Statistical analysis: All the available data were segregated, refined, and uploaded to an MS Excel spreadsheet and analyzed by SPSS version 25 in Windows format. The continuous variables were represented as mean, standard deviation, and median (IQR), frequencies, and percentages. Clinicopathological concordance was estimated using Cohen's Kappa statistic expressed as percentage agreement. Categorical variables were calculated by the square test for differences between groups, and a two-tailed p-value of <0.05 was considered statistically significant.

A total of n=60 cases of granulomatous skin lesions were included in the study. The baseline demographic profile of the cohort is presented in Table 1. The age range of the cohort was from 13 years to 66 years; the mean age of the group was 45.2 ± 16.8 years. The most frequently affected age group was 41 – 60 years with 41.7% of the cases, followed by 18 – 40 years with 33.3% of cases. A lower incidence was observed in cases above 60 years, with 16.7% of cases, and below 18 years, with 8.3% of cases. A slight preponderance was observed for males, with 53.3% of cases. The assessment of the duration of the lesion was less than 6 months in 58.3% of cases, which showed that most cases had relatively early presentation. The morphology of the lesions showed that papules and nodules were the most common in 46.7% of cases, plaques in 36.7% of cases, and ulcerative lesions in 13.3% of cases. The occurrence of lesions was common in the lower limb because these are the commonly exposed areas of the body. Table 1: Baseline Demographic and Clinical Characteristics of the Study Population Characteristic Category Number (n) Percentage (%) Age (Years) Mean ± SD 45.2 ± 16.8 <18 5 8.3 18-40 20 33.3 41-60 25 41.7 >60 10 16.7 Sex Male 32 53.3 Female 28 46.7 Duration of Lesion <6 months 35 58.3 6 months - 2 years 18 30 >2 years 7 11.7 Morphology of the lesion Papule/Nodule 28 46.7 Plaque 22 36.7 Ulcer 8 13.3 Other 2 3.3 Site of the lesion Head & Neck 15 25.0 Lower Limb 18 30.0 Trunk 10 16.7 Generalized 5 8.3 Histopathological analysis is given in Table 2. A critical analysis of the table showed that n=35 cases (58.3%), n=22 cases (36.7%), and n=3 cases (5%) were classified as infectious, non-infectious, and undetermined granulomatous dermatoses, respectively. The most common diagnoses were leprosy (33.3%) and cutaneous tuberculosis (16.7%), as well as deep fungal infection (8.3%). In non-infectious cases, the most frequent were sarcoidosis (13.3%) and granuloma annulare (11.7%), then foreign body granuloma (8.3%) and granuloma rosaceogenesis (3.3%). The observation of higher prevalence of infectious diseases such as tuberculosis and leprosy showed the regional endemicity of mycobacterial diseases. The presence of substantial cases of non-infectious origin showed a need for broad differential diagnosis in cases of granulomatous skin diseases. Table 2: Spectrum of Final Histopathological Diagnoses Diagnostic Category Specific Diagnosis Number (n) Percentage Infectious Granulomatous Diseases 35 58.3 Leprosy 2 33.3 Cutaneous Tuberculosis 10 16.7 Fungal Infections 5 8.3 Non-infectious Granulomatous Diseases 22 36.7 Sarcoidosis 8 13.3 Granuloma Annulare 7 11.7 Foreign Body Granuloma 5 8.3 Rosacea 2 3.3 Other / Unclassified 3 5.0 Total 60 100 The histopathological patterns of the granulomas observed in the cases of the study are given in Table 3. The analysis of the table showed that there were six major histopathological granuloma patterns in this cohort. The most prevalent one was the tuberculoid one, observed in n=18 cases (30%), which occurs mostly in tuberculoid leprosy and cutaneous tuberculosis. The sarcoidal pattern was observed in n=10 cases (16.7%), which were primarily related to sarcoidosis and silica granuloma. In n=8 cases (13.3%), necrobiotic granulomas were observed; the granulomas were normally related to granuloma annulare and necrobiosis lipoidica. Deep fungal granuloma was associated with suppurative granulomas (11.7%) of cases, and exogenous material deposits and tattoo reactions were associated with foreign-body type granulomas (8.3%). The histoid type, constituting 6.7% was associated with the cases of histoid leprosy. Mixed or unclassified patterns represented 13.3% and the shared histological characteristics of different granulomatous disorders. This pattern distribution has highlighted diagnostic heterogeneity and the importance of close clinicopathologic correlation. Table 3: Histopathological Patterns of Granulomas Observed Granuloma Pattern Associated Final Diagnosis (Most Common) Number (n) Percentage Tuberculoid Tuberculoid Leprosy, Cutaneous TB 18 30.0 Sarcoidal Sarcoidosis, Silica Granuloma 10 16.7 Necrobiotic Granuloma Annulare, Necrobiosis Lipoidica 8 13.3 Suppurative Deep Fungal Infections, TB 7 11.7 Foreign Body Foreign Body Reaction, Tattoo 5 8.3 Histoid Lepromatous Leprosy (Histoid type) 4 6.7 Mixed Unclassified Various 8 13.3 The comparison of the clinical and histopathological diagnoses is given in Table 4. The analysis of the table showed that complete concordance (identical diagnosis) was observed in n=38 cases (63.3%), whereas partial concordance (identical disease category, but different subtype) was observed in n=12 cases (20%). There were discordant results of incorrect clinical diagnosis in n=8 cases (13.3%), and some with no provisional diagnosis in n=2 cases (3.3%). The Cohen Kappa value of 0.65 was a good level of agreement between clinical and histopathological results. It also shows that clinical assessment may be sufficient for diagnosis in most cases of cutaneous granulomas. However, histopathological validation will be necessary, especially in the subtype classification of lesions and those with atypical manifestations. The findings support that a multidisciplinary approach is required for the arrival at a correct diagnosis, which ensures appropriate management. Table 4: Concordance Between Provisional Clinical and Final Histopathological Diagnosis Concordance Category Number of Cases (n) Percentage Full Concordance (Exact match) 38 63.3 Partial Concordance (Correct category, e.g., "Leprosy" but wrong type) 12 20.0 Discordant (Clinical diagnosis incorrect) 8 13.3 No Provisional Diagnosis (Clinically undiagnosed) 2 3.3 Total 60 100.0 Statistical measure Value Cohen's Kappa (K) 0.65 Strength of Agreement Good Table 5 presents the use of special stains for arriving at an etiological diagnosis in cases of the study. Special stains were very useful in diagnosis, with n=39 out of 60 of them being able to identify (65%). Mycobacterium tuberculosis infection was confirmed by Ziehl-Neelsen (AFB) staining in n=12 cases, and Mycobacterium leprae was confirmed through Fite-Faraco in n=18 cases, which proved that the patient had leprosy. PAS periodic acid -Schiff staining was performed on n=4 cases to identify fungal elements, and Gomori methenamine silver (GMS) staining was performed on n=5 cases to confirm the presence of fungi. These results underscore the fact that special stains are essential adjuncts to the normal hematoxylin and eosin, especially in distinguishing between infectious and non-infectious granulomatous lesions. The etiological specificity in the joint use of these stains was enhanced, which allowed concluding that the histopathology with special techniques added is the basis of correct diagnosis of granulomatous dermatoses. Table 5: Utility of Special Stains in Establishing Etiological Diagnosis Special Stain Number of Cases Where Stain was Positive / Diagnostic Primary etiology identified Ziehl-Neesen (AFB) 12 M. Tuberculosis Fite-Faraco 18 M. Leprae Periodic Acid—Schiff (PAS) 4 Fungal Elements Gomori Methenamine Silver (GMS) 5 Fungal Elements Total Cases Aided by Special Stains 39 65.0

Granulomatous skin lesions are chronic inflammatory skin diseases caused by a broad range of etiologies, both infectious and non-infectious. In the current study, a total of 60 cases with chronic skin lesions were included for analysis. The mean age of the patients was 45.2 years, and the frequency was the highest in the group of 41-60 years. Similar age predilection is also reported in a number of Indian studies, indicating that granulomatous dermatoses are a disease of older adults with few cases in lower age groups, as well as middle-aged individuals [1, 14]. The results of this study showed that the distribution of cases based on sex was approximately equal, which is in agreement with other similar studies by Chakrabarti et al. [1] and Potekar et al [4] who did not find any specific gender predilection for the occurrence of granulomatous dermatoses. The most common lesions found clinically were papular and nodular lesions, followed by plaques and ulcers, similar to findings reported by Kevadiya et al. [5]. The cases reported to the hospital in less than six months of the onset of the lesion suggested that these granulomatous dermatoses are symptomatic or cosmetically significant, and thus, early assessment was made. The most prevalent areas of occurrence were the lower limb and the head-neck area, which are likely to be more exposed to external trauma, infection, or foreign substance [6]. In the current study, infectious granulomatous dermatoses (58.3%) of cases were more than non-infectious (36.7%) of cases. A similar pattern has been shown in other Indian and Southeast Asian studies [1, 4, 7]. Leprosy was the most common diagnosis among the infectious causes, with the second cause being cutaneous tuberculosis, followed by fungi, which validates the endemicity of the mycobacterial diseases in the tropical countries [3, 5]. A similar pattern of results was observed by Ahmad et al. [9] and Bhat et al. [12], in which leprosy comprised most of the infectious granulomatous lesions. The persistence of leprosy is a major cause of concern and, therefore, needs continuous surveillance for early detection and treatment. The prevalence of sarcoidosis and granuloma annulare constituted more than one-third of the cases of non-infectious granulomatous lesions. Similar findings were reported by studies of Ting et al. and Khanna et al., where they found an increasing incidence of non-infectious granulomatous dermatoses being reported, probably due to increased awareness and application of diagnostic modalities. [10, 11] The histological features of sarcoidosis usually show compact, non-caseating, "naked" granulomas, and cannot be clinically diagnosed without histopathological confirmation of the absence of infectious causes [12]. The tuberculoid pattern was the most predominant in histology (30%), followed by the sarcoidal and necrobiotic ones, which is similar to reports of Chakrabarti et al. [1] and Kodnani et al. [8] in their respective studies. Pattern recognition, being a primary diagnostic procedure in histopathological analysis, can be emphasized by the existence of a variety of granuloma structures. Although, because of overlapping features, a clinical correlation as well as the use of special stains is required. The clinicopathological concordance rate of 63.3% observed in this study is comparable to previous reports, which have shown concordance ranging between 55–70% [4, 5, 7]. The calculated Cohen’s Kappa value of 0.65 indicated good agreement, affirming that while clinical suspicion is valuable, histopathology remains the gold standard for confirmation. Discordant cases mostly involved atypical or overlapping presentations, particularly in differentiating tuberculoid leprosy from lupus vulgaris and sarcoidosis, emphasizing diagnostic challenges in granulomatous pathology [9, 11, 14]. We found a clinicopathological correlation in 63.35% of cases in the study. This is similar to other studies where they found the rate of concordance from 55 – 70% of cases [4, 5, 7, 15]. The Cohen's Kappa calculated values in this study were 0.65, which showed a good agreement, showing that clinical suspicion is important, but histopathology remains the gold standard for confirmation. Discordant cases were due to atypical or overlapping features, which pose a challenge in cases of tuberculoid leprosy from lupus vulgaris and sarcoidosis. [9, 11] In this study, we used special stains for etiological confirmation of cases. The Ziehl–Neelsen stain was found to be positive in 12 cases, and the Fite–Faraco stain was positive in 18 cases. The use of PAS and GMS stains was done for confirmation of fungal infections, which were positive in 9 cases. Our findings were in agreement with other studies, which showed the diagnostic utility of special stains in 60 – 70% of cases of granulomatous dermatoses. [3, 10, 13] This shows that the use of histochemical as well as clinical findings leads to increased diagnostic accuracy and will guide appropriate management. At the end of our study, we highlight that leprosy is a common infectious etiology for granulomatous dermatoses, and non-infectious causes such as sarcoidosis require histopathological interpretation with special stains.

Within the limitations of the current study, we found that granulomatous lesions of the skin often present with overlapping clinical features. Therefore, histopathological examination is required for accurate diagnosis. Most of the causes of granulomatous lesions of the skin were infectious agents, which included leprosy and cutaneous tuberculosis. The non-infectious agents, such as sarcoidosis and granuloma annulare, were also found to be present in many cases. The common histopathological pattern observed was a tuberculoid granuloma. We used special stains for confirmation of diagnosis. This shows that clinicopathological correlation is required for precise identification and effective management of cases with granulomatous dermatoses.

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