Clinical diagnosis
Case 194
【Progress】
He received surgical mass resection at the day when he presented in our hospital. Histologic examination revealed dermatofibrosarcoma protuberans. He was scheduled to surgical operation again for wider resection because this tumor is categorized into intermediate soft tissue tumor.
【Discussion】
World Health Organization (WHO) categorized soft tissue tumor into three types: benign, intermediate and malignant. Intermediate type means local aggressive but rarely distant metastasis with the incidence less than 10% (1, 2). Dermatofibrosarcoma protuberans (or fibrosarcomatous dermatofibrosarcoma protuberans) belongs to intermediate type of fibroblastic/myo-fibroblastic tumors. Meanwhile, malignant type of those are adult fibrosarcoma, myxofibrosarcoma and sclerosing epithelioid sarcoma. The word of “Fibrosarcomatous” implies not so malignant as fibrosarcoma and not so benign, namely intermediate.
Dermatofibrosarcoma protuberans arises from dermis of trunk, extremity and neck. It slowly grows and rarely causes distant metastasis. Histologic examination using histologic stains of CD34 (marker of stem cell), Ki 67 (marker of cell proliferation) and desmin (tumor marker arisen from muscle) reveals positive with the incidence of more than 95% (3).
MRI is useful to grasp the whole tumor of dermatofibrosarcoma protuberans: low signal intensity on T1WI and high signal intensity on T2WI. As growing in size, degenerative necrotic area with very high on T2WI and very low on T1WI appears inside the tumor. Diffusion WI demonstrates high signal intensity and ADC values decreases. ADC values lowers as malignant character increases. It is reported that median ADC values (× 10-3mm2/sec) of benign and malignant tumors were 1.7 - 2.3 and 0.9 - 1.0, respectively (4-6). In our case, ADC values are 1.3 +/- 0.07 which is corresponded to be intermediate.
The main treatment for dermatofibrosarcoma protuberans is surgical resection. However, local recurrence rate is very high, 40 to 60% after simple resection and 0 to 40% after wide resection of 2 – 3 cm margin (3). Mohs surgery means microscopically controlled resection is often conducted for skin cancer. Recurrent rate after Mohs surgery is less than 10 %, indicating to surpass that after wide-resection surgery (3). Radiation therapy after surgical resection might be promising to prevent recurrence but no decent data is reported probably because of few cases. Targeted therapy using imatinib is scheduled after surgery or in case out of indication of surgery.
In our case,simple resection was conducted under impression of benign lesion. Because histologic examination revealed dermatofibrosarcoma protuberans, wide resection with 3 cm margin will be scheduled to perform near future.
【Summary】
We present a sixty two-year-old male with slowly growing subcutaneous mass. After simple resection, histologic examination revealed dermatofibrosarcoma protuberans. Then, he was scheduled to receive wide resection with 3 cm margin. It is borne in mind that dermatofibrosarcoma protuberans arises from dermis and, belongs to moderate category which is locally aggressive and rarely metastasis according to WHO classification. MRI with Diffusion WI might be useful to distinct between benign and malignant :median ADC values (× 10-3mm2/sec) of benign and malignant tumors were 1.7 - 2.3 and 0.9 - 1.0, respectively (7, 8). In our case, ADC values are 1.3 +/- 0.07 which is corresponded to be intermediate. The local recurrence is high 40-60% after simple resection followed by 0-40% after wide-resection and less than 10% after Mohs surgery.
【References】
1.Fletcher C, et al. World Health Organization classification of tumours of soft tissue and bone: pathology and genetics of tumours of soft tissue and bone, 4th ed. Lyon, France: IARC Press, 2013 [Google Scholar]
2.Akshay D, et al. Soft-Tissue Sarcomas: An Update for Radiologists Based on the Revised 2013 World Health Organization Classification. American Journal of Roentgenology. 2016;206: 924-932. 10.2214/AJR.15.15498
3.Li Y, et al. Clinical Features, Pathological Findings and Treatment of Recurrent Dermatofibrosarcoma Protuberans. J Cancer 2017; 8(7):1319-1323.
4.Torreggiani WC, et al Dermatofibrosarcoma Protuberans. MR Imaging Features. American Journal of Roentgenology 178(4):989-93 • May 2002
5.Pekcevik, Y, et al. Characterization of Soft Tissue Tumors by Diffusion-Weighted Imaging. Iran J Radiol. 2015 Jul; 12(3): e15478.
6.van Rijswijk CS, et al. Diffusion-weighted MRI in the characterization of soft-tissue tumors. J Magn Reson Imaging. 2002 Mar;15(3):302-7.
2020.6.17