a 65 years old male who presented with an elbow mass which had been present for 7 to 8 years

    Dr. Kyle white is a 3rd year resident in Dept of Pathology, Miller School of Medicine University of Miamia and presenting this case.


    Clinical history:

    The patient is a 65 years old male who presented with an elbow mass which had been present for 7 to 8 years, but he never received medical treatment. The patient recently felt increased in size and finally visited our orthopedic clinic due to his symptoms including numbness in the last 3 fingers. Physical examination was significant for a soft tissue mass involving the left elbow which measured up to 12.5 cm in maximum diamter. There was no erythema, ecchymosis, heat, or drainage noted.  The mass was soft, with multiple lobulations, and mobile. The skin overlying the mass was adherent. There was wasting of the hypothenar eminence and reduced sensation in the ulnar aspect while ROM of the elbow was intact.

    The patient had multiple imaging studies, including an MRI which showed focal collection in the subcutaneous tissues posterior and medial to the elbow with multiple septation. This was felt to likely represent a complex, septated ganglion cyst or chronic bursitis. Superimposed infection and/or neoplasm were also considered. During frozen section diagnosis, the pathologist was concerning of possible malignancy and the surgeon performed a wide complete excision.


    Microscopic examination:

    Histologic sections show a relatively well circumscribed large cystic tumor with small portion of solid area. The tumor contained variable sized cystic cavities comprising the vast bulk of the lesion (>80% cystic). The tumor occupied the deep dermis and subcutis. The epidermis was spared. The tumor is composed of a biphasic cellular population of polygonal cells with eosinophilic cytoplasm and smaller cells with clear cytoplasm.  Characteristic hyalinized vascular stroma and scattered intratumoral ductal differentiation found in some of solid lesion supported an eccrine origin skin adnexal tumor. Large areas of apocrine decapitation secretion and squamous differentiation were noted. No infiltrative growth was identified. Areas of hemorrhage and chronic inflammation were also present, likely a result of ruptured tumor cysts. The surgical resection margins were negative. In this particular case, there were atypical features including scattered nuclear pleomorphism in about 20-30% of tumor cells in both cystic and solid lesions and intratumoral heterogeneity of cell proliferation rate evaluated by Ki-67 immunostain (0-10%) and mitotic rate detected by PHH3 immunostain (0-10/ HPF).