Correlation of mast cell density and histopathological characteristics of syringoma: An immunohistochemical study

Background Syringoma, a benign skin tumour characterised by stromal fibrosis and epithelial encirclement, suffers from limited treatment options. Aim This study aimed to analyse the correlation between mast cell density and histological features of syringomas, particularly stromal fibrosis and epidermal pigmentation. Methods Immunohistochemical staining with CD117 and estrogen receptor (ER)-α was performed in 49 samples from 47 patients of syringoma to assess mast cell density and ER-α expression. Results The study revealed a female predominance (4.2:1), with a median age of 42 years (range, 21-80 years) and an onset at the age 28.5 years (5-74). All 49 cases were localised, primarily to the eyelid (67.3%), followed by the face (18.4%), vulva (8.2%), and axilla/extremities (6.1%). Epidermal thickness correlated directly with tumour thickness (r=0.652, p<0.01), which varied across anatomical sites. Mast cell density significantly correlated with basal pigmentation (r=0.338, p=0.02), stromal fibrosis (r=0.308, p=0.03), and stromal ER-α (r=0.249, p=0.03), suggesting their involvement in syringoma pathogenesis. Acanthosis, basal hyperpigmentation, and stromal fibrosis were prevalent in 83.7%, 83.7%, and 100% of patients, respectively. ER-α positivity was observed in the syringoma stromal area in 30 cases (61.2%), whereas positivity in the tumour cell area was confirmed in only 3 cases (6.1%). Limitations The retrospective nature of the analysis and the limited sample size may affect the generalisability of the findings. Conclusion Our findings highlight a significant correlation between mast cells and stromal fibrosis, as well as basal hyperpigmentation in syringomas. This suggests the potential involvement of mast cells in their pathomechanism. Furthermore, the correlation of mast cell density with stromal ER-α may explain the female predominance.