Cutaneous pseudolymphoma: A clinicopathological study and immunohistochemical patterns

Background: Cutaneous pseudolymphoma can histologically and clinically simulate various types of cutaneous lymphoma. We conducted the current study to evaluate the clinicopathological and immunohistochemical (IHC) aspects of cutaneous pseudolymphoma (PSL). Methods: 30 cases of cutaneous PSL were selected from the archives of 2013-2017 in Shahid Faghihi Hospital pathology lab, Shiraz University of Medical Sciences. Available clinical data, histopathological features and IHC findings were statistically analyzed. Results: The female: male ratio was 2:1 and the median age was 47±14.9 years. The lesions were located on the head and neck 26 (86.7%), trunk 2 (6.7%) and extremities 2 (6.7%). 23 (76.7%) cases had nodular pattern, while 7 (23.3%) showed diffuse pattern. The grenz zone was seen in 24 (80%) cases. Sixteen (53.3%) cases showed top heavy infiltration, 11 (36.7%) showed the same distribution of infiltration at the superficial and deep dermis, often involving the subcutaneous fat and 3(10%) showed bottom heavy infiltration. In IHC, 11(36.6%) cases showed the B cell type, 10 (33.3%) T cell type and 9 (30%) mixed type (B and T cells). Conclusion: None of the cases was suspicious for cutaneous lymphoma, applying IHC staining. Gender distribution, and the site of cutaneous lesions were similar to previous studies. The most common histological subtype was nodular, while the B-cell cutaneous pseudolymphoma was slightly more common compared to the T-cell type.