Complete remission of a periorbital dermatofibrosarcoma protuberans with adjuvant imatinib mesylate in a child

Pediatric dermatofibrosarcoma protuberans: A clinicopathologic and genetic analysis of 66 cases in the largest institution in Southwest China

Background

Dermatofibrosarcoma protuberans (DFSP) is an uncommon cutaneous tumor in children. Most published articles are sporadic or small series and lack systematically molecular analyses. The aim of our study is to better understand the clinicopathologic and genetic features of these rare lesions.

Methods

All patients diagnosed with DFSP aged ≤ 18 years were retrospectively reviewed from January 2006 to May 2022.

Results

A total of 66 cases (32 male and 34 female patients) were identified, with ages ranging from 0.3 to 18 years (median, 13 years). Tumor locations predominantly occurred on the trunk (38/66, 57.6%), followed by the extremities (20/66, 30.3%) and head/neck (8/66, 12.1%). Histological findings revealed classic (41/66, 62.1%), myxoid (4/66, 6.1%), pigmented (6/66, 9.1%), plaque-like (3/66, 4.5%), giant cell fibroblastoma (GCF; 6/66, 9.1%), and fibrosarcomatous (6/66, 9.1%) variants of DFSP. Immunochemistry revealed minority tumors (9/66, 13.6%) showing patchy or negative staining for CD34. Fluorescence in situ hybridization (FISH) indicated that 49 of 53 tested cases including all detected biopsy specimens (11/11) contained COL1A1-PDGFB fusion, in which the average copy number gain of COL1A1-PDGFB was 0.68. There were four cases negative for COL1A1-PDGFB rearrangement, one of which was found to harbor a novel COL3A1-PDGFB fusion by next-generation sequencing (NGS). Treatment for 63 patients comprised 40 marginal excisions and 23 wide local excisions (WLEs), including 1 with imatinib therapy. Follow-up information was available on 49 patients with a duration of 12-161 months (median, 60 months). Fourteen patients developed tumor recurrence, all with initial marginal excisions. The others survived with no evidence of disease.

Conclusions

This study of pediatric DFSP indicates certain discrepancies in clinicopathologic characteristics between children and adults. The majority of pediatric DFSPs contain COL1A1-PDGFB fusion, the same as their adult counterparts. The COL3A1-PDGFB chimerism might be associated with the special morphology of GCF, which needs further investigation. FISH is valuable in biopsy tissues and cases with atypical CD34 immunostaining, while supplementary NGS could be helpful to identify the cytogenetically cryptic DFSP. Overall, an urgent accurate diagnosis is needed to formulate an optimal therapeutic strategy in the pediatric population.

Dermatofibrosarcoma Protuberans in Children

OPINION STATEMENT

Paediatric dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue malignant tumour which displays aggressive local behaviour and has low metastatic potential. The diagnosis is often delayed as DFSP is usually mistaken for other skin conditions, particularly in the early stages of disease. DFSP tends to follow an indolent course after the initial presentation with what is often described as a "rubbery lump". As the disease progresses, the lump tends to enlarge, change colour, and exhibit a more nodular consistency. In rare cases, DFSP can present as an ulcerated exophytic lesion or a depressed area of skin, making diagnosis even more challenging. A high index of suspicion is warranted for early diagnosis, and referral to a specialist unit with expertise in both oncologic resection and reconstruction. DFSP tumours arise from the dermis and grow with finger-like projections. Therefore, in cosmetically sensitive or functionally important locations, an excision and analysis technique that assesses all excision margins is the gold standard of care. Slow Mohs technique performed with en bloc excision is a well-tolerated option for oncologic resection of the tumour. Mohs technique can also be considered but can be challenging in children for reasons explained below. As an alternative, depending on the anatomical location, tumours can be excised with a wide local excision. While an excision technique that incorporates the deep fascia with a 3-cm peripheral margin is acceptable in adults, planning of the excision margin in children should involve consideration of preoperative imaging with MRI, site of the tumour, age, and physical built of the child. Patients should be offered all treatment options considering the local outcomes, available expertise, and cost. A multidisciplinary approach and good communication between team members is crucial. Close collaboration with a pathologist who is familiar with sectioning technique that allows margin control is of paramount importance. Soft tissue reconstruction should be performed immediately after oncologic clearance, although a staged approach may be required. Adjuvant radiotherapy should be avoided in children due to the long-term risk of secondary malignancies and potential for growth disruption.

Dermatofibrosarcoma protuberans in children and adolescents: Primary and Relapsed disease-Experience of the Cooperative Weichteilsarkomstudiengruppe (CWS)

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a rare low-grade tumor. Little is known about best treatment of primary and relapsed disease (RD).

METHODS

Treatment and outcome of 40 patients with DFSP prospectively registered within the CWS-96 and -2002P trials and the registry SoTiSaR (1996-2016) were analysed.

RESULTS

Median age was 8 years (range, 0.64-17.77). Fluorescence in situ hybridization analysis to detect COL1A1-PDGFB fusion genes was positive in 86% (12/14) of evaluated patients. Primary resection was performed in all patients. Patients had IRS group I (n = 28), II (n = 9), and III (n = 2); not available (n = 1). To achieve complete remission (CR), a secondary resection was performed in 18 patients resulting in microscopically complete (R0, n = 34/40) and microscopically incomplete (R1, n = 5/40) resection. All patients achieved CR. The 5-year event-free survival (EFS) and overall survival was 86% (±12; CI, 95%) and 100% (±0; CI, 95%), respectively. R0 resection/IRS I was significantly favorable for the 5-year EFS. Local relapse occurred after a median time of 1.1 years (range, 0.04-5.1) in 15% (6/40) after CR. All patients with RD underwent resection and achieved CR. Three patients had fibrosarcomatous DFSP, two were alive after R0 resection.

CONCLUSION

Complete surgical resection is mandatory to prevent relapse of DFSP.

Incidence and Outcomes of Dermatofibrosarcoma Protuberans in the US Pediatric Population

BACKGROUND

Dermatofibrosarcoma protuberans (DFSP) is a low-grade soft tissue sarcoma. In the pediatric population, DFSP is exceedingly rare. Aim of this study was to describe the epidemiology and clinical outcomes in a large pediatric cohort.

METHODS

Surveillance, Epidemiology, and End Results (SEER) database (1973-2010) was analyzed for all patients with dermatofibrosarcoma occurring in patients <20 years of age. Data were extracted based on age, gender, race, anatomic site, histology, stage, treatment modalities, and survival. Incidence rates were standardized to the 2000 US population.

RESULTS

A total of 451 patients were identified. Overall annual incidence was 0.10 per 100,000. Incidence was highest among black children and adolescents (ages 15 to 19 years). Trunk was most common site, followed by extremities. Head and neck region was least common site (P < 0.05). Majority (54%) of patients presented with localized disease. Overall, 95% underwent surgery. Only 2.2% were treated with perioperative radiation therapy. Overall prognosis was favorable with 5-year overall survival (OS) of 100%, 15-year OS of 98%, and 30-year OS of 97%. Median survival was 117 months. Male patients had lower 15- and 30-year OS compared with females (P < 0.05).

CONCLUSION

Pediatric DFSP has lower incidence but similar clinical characteristics to adults. Incidence is higher in black children and in the trunk region. While prognosis is favorable, male sex is associated with decreased OS.