RESEARCH POSTER PRESENTATION DESIGN © 2015 www.PosterPresentations.com 90 year old Caucasian man with history of several non- melanoma skin cancers, presented with a 4.0 x 2.5 cm ulcerated, friable, exophytic mass on the left mid frontal scalp of two months duration. The patient had previously presented two months earlier with non-healing scalp lesion. At that time, the lesion was a 0.9 cm ulcerated, erythematous, papule. A shave biopsy of the lesion was performed however the histopathology was non-diagnostic and demonstrated marked parakeratosis, fibrosing granulation tissue in the upper dermis, with a massive neutrophilic infiltrate. A repeat biopsy was performed of the exophytic mass for diagnostic and de-bulking purposes. The histopathology of the re-biopsy demonstrated an ulcerated tumor filling the dermis. The tumor cells were pleomorphic, spindled, arranged in vague fascicles, and extended to the deep margin. The cytology was markedly atypical, with large irregular nuclei, prominent nucleoli, and numerous mitoses, including atypical forms. Immunohistochemical analysis was performed. The tumor cells were diffusely positive for CD10 and weakly positive for CD68. Cytokeratin AE1/AE3, desmin, S-100, EMA, cytokeratin 5, p63, Mart-1, smooth muscle myosin, procollagen 1, ERG, CD31, and CD 34 were all negative. History Physical Exam Figure 2-4. Histopathology of the lesion. The excision specimen reveals the extent of tumor invasion. Tumor cells infiltrate the dermis and the deep subcutis (H&E, 40X total magnification). The tumor cells are spindled and arranged in vague interlacing fascicles with focal areas of necrosis (H&E, 200X total magnification). The tumor cells are pleomorphic with large, irregular nuclei, prominent nucleoli, and moderately abundant eosinophilic cytoplasm. Mitoses are readily identified, including atypical forms (H&E, 400X total magnification). Histopathology The patient subsequently underwent wide local excision with one centimeter margins. The specimen showed atypical spindled cells extending deep into subcutaneous tissue. Due to the depth of invasion with involvement of subcutaneous tissue and the presence of necrosis, the lesion was diagnosed as an undifferentiated pleomorphic sarcoma of skin. The margins were free of tumor however the patient was referred to oncology for further evaluation and consideration of adjuvant therapy. The patient and family declined oncology referral, and as of four months post-excision, there was no evidence of recurrence. Clinical Course Discussion Undifferentiated pleomorphic sarcoma (UPS) of skin can clinically and histopathologically mimic atypical fibroxanthoma (AFX). Distinguishing between the two is important, as the prognoses of these tumors are vastly different. AFX follows more of a benign course, typically recurs only after incomplete excision, and rarely metastasizes. UPS, previously grouped into the malignant fibrous histiocytoma (MFH) category, is more aggressive in nature, and has a high rate of recurrence along with malignant/metastatic potential. Clinically, AFX presents as a rapidly growing solitary nodule on sun-damaged, actinic skin of the elderly, usually on the head and neck region. UPS is considered a soft tissue tumor but can occur superficially in the skin, with a presentation mimicking AFX. Histologically, UPS and AFX consist of spindle shaped cells arranged in a fascicular pattern and can exhibit multinucleation, pleomorphism, and mitotic figures. UPS is distinguished from AFX by deep subcutaneous involvement, perineural and/or lymphovascular invasion, and necrosis. Immunohistochemically, both stain negative for S-100/SOX-10, cytokeratin, CD31/CD34, and desmin/myosin allowing differentiation from other pleomorphic tumors in the skin, such as melanoma, squamous cell carcinoma, angiosarcoma, and leiomyosarcoma. AFX and UPS are diagnoses of exclusion, requiring broad lineage- specific immunohistochemical analysis to exclude other poorly differentiated tumors. References 1. Bolognia JL, Jorizzo JL and Rapini RR. Fibrous and fibrohistiocytic proliferations of the skin and tendons, atypical fibroxanthoma. In: Dermatology, 3rd ed, Elsevier, 2012. p 1973. 2. Goldblum JR, Folpe AL and Weiss SW. Undifferentiated pleomorphic sarcoma. In: Enzinger and Weiss's Soft Tissue Tumors, 6 th ed, Elsevier, 2014 p 421-442. 3. McKee PH, Calonje E and Granter SR. Connective tissue tumors, atypical fibroxanthoma, malignant fibrous histiocytoma. In: Pathology of the Skin, 4th ed, Elsevier, 2012. p 1658-1662. 4. Luzar B and Calonje E. Morphological and immunohistochemical characteristics of atypical fibroxanthoma with a special emphasis on potential diagnostic pitfalls: a review. J Cutan Pathol. 2010 Mar;37(3):301-309. 5. Miller K, Goodlad JR and Brenn T. Pleomorphic dermal sarcoma: adverse histologic features predict aggressive behavior and allow distinction from atypical fibroxanthomas. Am J Surg Pathol. 2012 Sep;36(9):1317-1326. 6. Beer TW, Drury P, and Heenan PJ. Atypical fibroxanthoma: a histological and immunohistochemical review of 171 cases. Am J Dermatopathol. 2010 Aug;32(6):533-540. 7. Mirza B, and Weedon D. Atypical fibroxanthoma: a clinicopathological study of 89 cases. Australas J Dermatol. 2005 Nov;46(4):235-238. There is significant overlap between AFX and UPS of skin clinically, morphologically, and immunohistochemically. Histologically, there are identifiable differences found on excision of the lesion. Distinguishing the two requires complete excision to evaluate for aggressive features, specifically the tumor’s extent of invasion, with AFX designated to tumors restricted to the dermis. UPS of skin invades deeply into subcutaneous tissue and can demonstrate tumor necrosis, perineural or lymphovascular invasion. These features are consistent with its more aggressive course including recurrence and metastatic potential. Undifferentiated pleomorphic sarcoma is a rare entity with confusing, misleading, and changing nomenclature previously named malignant fibrous histiocytoma. Undifferentiated pleomorphic sarcoma of skin is a diagnosis of exclusion made after complete excision with histology aided by immunohistochemistry. The correct diagnosis is crucial to optimal outcome, preventing mismanagement of an aggressive and potentially fatal tumor. Figure 1. Clinical presentation of lesion . Left mid frontal scalp with rapid growing, ulcerated, 4 x 2.5 cm exophytic mass. 1 University of North Texas Health Science Center, Forth Worth, TX; 2 ProPath, Dallas, TX Michael Carletti DO 1 , Peter Malouf DO 1 , Zachary Ingersoll MS-III 1 , Greg Hosler MD, PhD 2 , Stephen Weis DO 1 Undifferentiated Pleomorphic Sarcoma of Skin: Clinical and histopathologic emulator of atypical fibroxanthoma, distinction imperative