A Rare Cause of Back Pain: A Case Report with Histopathological and Radiological Findings of an Unusually Located Pilomatricoma

Abstract

IntroductionPilomatrixoma, also known as pilomatricoma or calcifying epithelioma of Malherbe, originates from the cells of the hair matrix. This tumor is an asymptomatic, slow-growing, benign dermal neoplasm [1]. The lesions are typically found in the head and neck (68.2%) and then the trunk (14.4%) and the upper (15.3%) and lower extremity (2%) [1]. These tumors are more common in the second decade of life (60-70%). A typical pilomatricoma is a hard, calcified Case ReportA 26-year-old woman presented with a 1-year history of soft tissue swelling and pain in her right dorsal trunk. Clinical examination revealed a solitary, firm, well-circumscribed mass located on the right dorsal trunk. In addition, the overlying skin showed bluish discoloration. There was no history of trauma or major surgery in this area. General physical examination and laboratory findings were normal. Direct radiography was normal. MR imaging showed a well-circumscribed hypointense lobulated mass in the right dorsal trunk on the axial T1 Weighted Image (WI) ( Figure 1). On the axial T2WI ( Figure 2a) and sagittal (Figure 2b), the mass was non-homogeneous and isointense to the muscle. There was no fat suppression within the mass. Primarily, the lesion was thought to be a benign mass. The lesion was completely excised under regional anesthesia and closed directly. The surgical specimen revealed a hard well-circumscribed mass, measuring 3x2x1 cm, and was yellowish-white ( Figure 3). Histopathological examination of the pilomatricoma showed basaloid and shadow cells (Figure 4 (a,b)). There was no atypical cell or invasion of surrounding soft tissue. A final diagnosis of pilomatricoma was made histopathologically. There was no recurrence at follow-up 6 months later. DiscussionA pilomatricoma is a superficial, firm, solitary, slow-growing, painless dermal or subcutaneous mass. It is often 0.5 to 3 cm diameter. The overlying skin normally has bluish discoloration. Pilomatricomas are slightly more common in women [2], and are frequently observed Sayit E, et al., J Orthop Res Physiother 2015, 1: 003 DOI: 10.24966/ORP-2052 HSOA Journal of Orthopedic Research and Physiotherapy Case Report AbstractPilomatricoma is a benign neoplasm of the skin that originates in a hair follicle. Pilomatricoma is usually located on the head and neck, trunk, or upper and lower extremities and is most common during the first two decades of life. Pilomatricoma are slightly more common in women than men. The masses are usually asymptomatic and solitary, firm, mobile, dermal or subcutaneous nodules. Involvement of the dorsal trunk is uncommon, and pilomatricomas can be mistaken as other subcutaneous soft tissue lesions. Therefore, diagnostic imaging methods are useful for differential diagnosis. Here, we present an unusual case with MR imaging and pathologic findings of a dorsal trunk pilomatricoma in a 26-year-old woman.