We present an 81-year-old man who presented for evaluation of an indurated plaque with an exophytic, pearly, skin-red-brown colored nodule with central ulceration on his chest that evolved over the course of several months and was initially suspected to be basal cell carcinoma. Biopsy demonstrated histological features of dermal spindle cell proliferation in a storiform fashion with CD34 positivity confirming a diagnosis of dermatofibrosarcoma protuberans (DFSP). Dermatofibrosarcoma protuberans are rare, slowly progressive soft tissue sarcomas. The rate of DFSP is greatest among African Americans (8.3/1,000,000), occurring nearly twice as frequently when compared to Caucasians. Aside from race/ethnicity, age, and skin trauma, no specific risk factors are associated with DFSP. Complete excision is curative. Given its pearly skin colored appearance, papular/nodular/atrophic morphology variants, and tendency to form indurated plaques, DFSP may be mistaken for nodular and morpheaform basal cell carcinoma subtypes, as well as a variety of other conditions. This case highlights the importance of maintaining DFSP on the differential diagnosis of slowly progressive nodules and indurated plaques, especially in African Americans.

Dermatofibrosarcoma protuberans (DFSP) is an uncommon intermediate-grade soft tissue sarcoma. The tumor is found preferentially on the trunk, whereas the head and neck region are affected in only 10% to 15% of cases. We report the case of a 44-year-old woman with a 5-month history of an asymptomatic, firm, yellow nodule in the mucosa of the right cheek measuring 2.5 cm. The clinical diagnosis was lipoma and an excisional biopsy was obtained. Histopathological analysis revealed a proliferation of spindle-shaped mesenchymal cells arranged in interlacing fascicles amidst fibrous stroma. Low mitotic activity (2 mitoses per field) and deep cell infiltration into adipose tissue were observed. These features led to the histopathological diagnosis of a malignant low-grade mesenchymal cell tumor. Immunohistochemical analysis revealed negative staining for α-SMA, S-100, and Bcl-2, but positive staining for Ki-67 (18%) and strong and diffuse staining for CD34. These findings were compatible with the diagnosis of DFSP. Only two cases of DFSP in the oral cavity, both involving the cheek mucosa, have been described so far, highlighting the rarity of the present case.

Fibrous hamartoma of infancy (FHI) is a rare benign soft tissue tumor with a triphasic organoid histologic appearance. The authors present a case of a 21-month-old healthy girl with a slowly growing flesh-colored subcutaneous plaque 12cm in size on the lower back, with overlying hypertrichosis. A punch biopsy revealed a proliferation of spindle cells infiltrating the dermis and hypodermis organized in a dense storiform pattern with a strong diffuse positivity for CD34. The diagnosis of congenital dermatofibrosarcoma protuberans (DFSP) was considered and an excision was performed. Histopathologic analysis showed an extensive poorly demarcated mass infiltrating the dermis and hypodermis, composed of different components: a monomorphous fibroblastic/myofibroblastic component, a mature adipose component, and an immature mesenchymal basophilic component. The clinical aspects with the histologic and immunohistochemical features led to the diagnosis of giant fibrous hamartoma of infancy. In our case the strong diffuse CD34 positivity was a diagnostic pitfall leading to an incorrect hypothesis of congenital DFSP. The characteristic triphasic histology of FHI was missed owing to the small size of the punch biopsy. This article highlights the importance of being aware of the CD34+ dermal mesenchymal tumor differential diagnosis and the necessity of appropriate size biopsies to avoid sampling error.

Mohs micrographic surgery (MMS) is a breakthrough surgical technique that has changed the management of neoplasms in dermatology. Through continued practice and evolution, MMS now can successfully treat a variety of rare non-melanocytic cutaneous malignancies for which achieving remission and the optimal aesthetic result after surgery was previously challenging. Mohs micrographic surgery has utility for conditions besides melanoma. Herein, we discuss this versatility of Mohs micrographic surgery. Specifically, Mohs micrographic surgery can be successfully used for cases such as dermatofibrosarcoma protuberans, atypical fibroxanthomas, extramammary Paget disease, Merkel cell carcinoma, sebaceous carcinoma, and microcystic adnexal carcinoma.

Multiple clustered dermatofibromas describes a confluence of dermatofibromas in one anatomic location. We describe a 32-year-old man who presented for evaluation owing to skin papules and plaques and concerns about malignancy. Repeat histopathological evaluation found no evidence for dermatofibrosarcoma protuberans. Our case presents this relatively rare condition and discusses observation along with potential treatment options.

BACKGROUND: Mesenchymal neoplasms of the uterus encompass a diverse group of tumors, with varying characteristics and origins, collectively accounting for 8% of uterine malignancies. The most common variants include uterine leiomyosarcoma, low-grade and high-grade endometrial stromal sarcoma, adenosarcoma, and undifferentiated sarcoma. Clinical presentation is often nonspecific and can lead to delayed diagnosis. Uterine sarcomas are generally aggressive, resulting in poorer prognosis compared to carcinomas. Recent advances in molecular techniques, such as next-generation sequencing (NGS), have led to the identification of new subtypes of uterine sarcomas, including COL1A1::PDGFB fusion-associated fibrosarcoma, which has a specific chromosomal translocation t(17;22)(q22;q13). Imatinib, a tyrosine kinase inhibitor (TKI), is an effective treatment for dermatofibrosarcoma protuberans (DFSP), marked by this translocation. CASE: We present the case of a 42-year-old woman diagnosed with COL1A1::PDGFB fusion-associated uterine fibrosarcoma. The patient underwent total hysterectomy and excision of the tumor, initially misdiagnosed as a low-grade leiomyosarcoma. Subsequent histological examination, immunohistochemistry, and fluorescence in situ hybridization (FISH) confirmed the diagnosis. After 10 months, disease recurrence was detected, and Imatinib therapy was initiated at a dose of 400 mg daily. An allergic reaction led to a temporary discontinuation, but upon resumption with appropriate medication, a positive radiological response was observed. The patient achieved a complete remission after 2 years and is still on Imatinib treatment. CONCLUSIONS: COL1A1::PDGFB fusion-associated uterine fibrosarcoma is an extremely rare mesenchymal neoplasm. In a case we present herein, we treated a patient with imatinib as first-line medical therapy. The patient is currently in complete remission after 37 months from treatment start. To the best of our knowledge, this represents a unique observation. We also provide a detailed literature review of the published cases so far. Prospective case series are needed to further understand the natural history of these tumors and optimize treatment strategies.