Extensive Eccrine Squamous Syringometaplasia Mimicking Squamous Cell Carcinoma on Histopathology

Abstract

Eccrine Squamous Syringometaplasia (ESSM) is a histologically distinctive skin eruption occurring predominantly in acral or intertriginous areas presenting as erythematous macules, papules or patches. It is a response of eccrine ducts and glands to any injury or inflammation. The cuboidal epithelium of eccrine ducts and glands undergoes metaplasia and transforms to keratinised squamous epithelium in ESSM. Other types of metaplastic changes encountered are squamous, mucinous and adenomatous. In squamous syringometaplasia, the metaplastic squamous cells form lobules and florid types can pose a diagnostic dilemma, which if not well understood may lead to an erroneous diagnosis of neoplasia. Literature suggests ESSM as a condition associated with another pathogenic stimuli or therapy; however florid ESSM is very rare. Hereby, the authors present a case report of a 43- year- old male who presented florid ESSM mimicking well-differentiated Squamous Cell Carcinoma (SCC). The present case presented with a non healing elevated lesion on anterior aspect of right leg with itching. Similar lesions were not present in any other part of the body. The patient did not have history of any systemic disease or drug intake. The lesion was excised and sent for histopathology. On gross examination the skin showed irregular thickening and foci of erosion. Microscopy showed acanthotic, hyperkeratotic epidermis and dermal ESSM. There were irregular clusters of metaplastic squamous cell in dermis, resembling invasive islands of SCC. Meticulous examination revealed lobulated architecture of ESSM, lack of individual cell keratinisation/significant atypia or mitosis. The present report highlights the significance of histopathological diagnosis of benign squamous proliferations which can mimic malignancy and cause undue stress to the patient.