Pancreatic metastasis of dermatofibrosarcoma protuberans: a rare case

Abstract

Dermatofibrosarcoma protuberans (DFSP) is a rare soft tissue malignancy which is locally aggressive, slow growing. It has a very low metastatic potential and has high risk of local recurrence. We report a 65-year-old man with recurrent DFSP of thigh with pancreatic metastasis. Apart from our patient, only four other cases of pancreatic metastasis of DFSP have been reported. Our patient had a solitary metastasis to pancreas and was treated with distal pancreaticosplenectomy. Outcome of the patient was good. We present this case report to emphasise that resection may be considered for solitary metastasis of DFSP and can be managed successfully.

Background

Dermatofibrosarcoma protuberans (DFSP), first described by Darier and Ferrand in 1924, is a relatively rare skin tumour.¹ DFSP is a locally aggressive tumour arising from fibroblasts in subcutaneous mesenchymal tissue of the skin, exhibits local recurrence and rarely systemic metastasis. Most appear on trunk (50%), proximal extremities (20%–35%), head and neck (10%–15%).¹ Lesions appear as smooth, flesh coloured nodules in or immediately beneath the skin and generally manifest in patients between 20 and 50 years of age.¹ Cytogenetically the majority of DFSP displays the t(17:22)(q22:q13) translocation, which fuses the COL1A1 and platelet-derived growth factor B (PDGFB) genes and accounts for its PDGFB over expression.² Translocation of t(17:22) has been found in 90% of DFSP. Adjuvant radiation therapy has been used effectively after resection for recurrences. Because of the PDGFB upregulation, patients with unresectable disease may be treated with neoadjuvant imatinib.²

We wrote up this case because to learn that solitary metastasis of DFSP can be managed successfully with resection.

Case presentation

A 65-year-old man presented 5 years ago to outside hospital with swelling over medial aspect of left thigh, following stab injury over the area few months ago. Following which patient underwent wide local excision. Histopathology showed DFSP with margins positive. Following which patient was advised radiotherapy and so underwent adjuvant radiation therapy 54 Gy in 27 fractions.

After a disease-free survival of 4 years patient came to our institute with history of recurrent swelling at the operated site and underwent reresection (wide local excision with local advancement flap with split skin grafting). The histopathological examination was reported as pT2 pN0 fibrosarcomatous DFSP with tumour size of 7×6.5×4 cm (figure 1). Distance of tumour from all the margins is about 3 cm and from deep resected margin is about 0.5 cm close to fascia and vessels. After discussing with tumour board, patient underwent reirradiation of 54 Gy in 27 fractions.

Figure 1.

H&E Showing spindle cells arranged in herringbone fashion.

In February 2019 patient had persistent non-healing ulcer for which local recurrence was suspected. He underwent biopsy and staging work up was done. Local biopsy showed no tumour, Positron emission tomography-CT (PET-CT) showed fluorodeoxyglucose (FDG) avid heterogenous mass lesion in tail of pancreas (measuring 73×63 mm, SUV max 10.2), superiorly lesion abuts the lesser curvature of stomach, posteriorly lesion abuts the splenic vein and splenic artery with no uptake in another sites (figure 2). Tumour board discussion was done and CT guided biopsy of pancreatic mass was done showed findings consistent with diagnosis of DFSP metastasizing to pancreas (figure 3A). The tumour tissue was diffusely positive for vimentin, CD34, Ki67 10%, negative for BCL-2 (figure 3B).

Figure 2.

Positron emission tomography-CT scan showing heterogenous mass lesion in tail of pancreas (measuring 73×63 mm, SUV max 10.2), superiorly lesion abuts the lesser curvature of stomach, posteriorly lesion abuts the splenic vein and splenic artery with no uptake in another sites. The arrow shows the mass in the tail of pancreas.

Figure 3.

(A) H&E showing neoplastic spindle cells in pancreas from the biopsy. (B) Immunohistochemistry showing Ki67 of 10%.

Description

Fluorodeoxyglucose.

Investigations

Patient underwent PET-CT for staging work up which showed FDG avid heterogenous mass lesion in tail of pancreas (measuring 73×63 mm, SUV max 10.2), superiorly lesion abuts the lesser curvature of stomach, posteriorly lesion abuts the splenic vein and splenic artery with no uptake in another sites (figure 2).

Treatment

Patient underwent distal pancreatosplenectomy (figure 4A–D). Histopathology examination (HPE) report showed metastatic deposit with tumour infiltrating into pancreas, immunohistochemistry (IHC) of lesional cells are positive for vimentin, platelet-derived growth factor receptor (PDGFR), Ki67 20% (figure 5A, B).

Figure 4.

(A, B) Intraoperative image showing mass arising from tail of pancreas. (C, D) Resected specimen of distal pancreaticosplenectomy.

Figure 5.

(A) 400× H&E showing neoplastic spindle cells in pancreatic tissue. (B) Magnified H&E showing spindle cells arranged in storiform pattern.

Outcome and follow-up

After surgery patient has been doing well and is being able to return to his work. He is on regular follow-up.

Discussion

DFSP is a soft tissue neoplasm of which is considered as a low-grade sarcoma with low metastatic potential.¹ However, metastasis have been reported in 1%–6% of patients, and are a sign of poor prognosis, most often resulting in death within 2 years.¹ Pancreatic metastasis of DFSP is extremely rare; only four cases have been reported. In one case, autopsy revealed pancreatic metastasis after the patient died of brain metastasis. The other patient was diagnosed as having a mass in the head of the pancreas and had undergone pancreaticoduodenectomy.¹Twenty to fifty years is the common age of occurrence with male predominance, children can also be affected.³ Although DFSP lesions have low metastatic potential, they have a tendency to recur, occurring in 80%–90% of cases with having local recurrence of 26% and risk of distant metastasis of 5%.³

Fibrosarcomatous variant (DFSP-FS) has about 58% chance of local recurrence and about 15% chance for distant metastasis.³ Lung is the most common site of metastases occurring via haematogenous spread.⁴ Among the various histological subtypes, DFSPs with DFSP-FS areas may have a more likelihood of adverse outcomes. DFSP-FS tends to have higher proliferative activity than DFSP without FS area and hence has metastatic potential.⁵ In all excised lesions, that is, the primary lesion, and the metastatic lesion in the pancreas, have a fibrosarcomatous area, herringbone pattern, and a high number of mitoses (10 mitoses per 10 high-power fields).⁵ Immunohistochemically, the fibrosarcomatous cells will be positive for vimentin, PDGFR, negative for S100, SMA, CD117, DOG1, TLE1, Ki67. DFSP-FS shows remarkably diminished or absent CD34 immunoreactivity.^{5 6}

Regarding therapy, wide local excision with tumour-free margins is necessary to avoid local recurrence. For achieving this, removal of a 2–3 cm wide margin of visibly uninvolved tissue along with underlying fascia is necessary.⁶ Because of its low metastatic potential, patients with solitary resectable tumours may be considered for curative resection.

Imatinib mesylate is a selective low molecular weight inhibitor of the PDGF receptor tyrosine kinase, which controls the tumour growth by inhibiting the PDGF-mediated autocrine or paracrine loop of tumour growth. It has proven effective in locally advanced, irresectable or disseminated FS-DFSP with translocation between chromosomes 17 and 22.⁷ Newer tyrosine kinase inhibitors such as sunitinib, duratinib and multikinase inhibitors like nilotinib have also been developed.⁸ Radiotherapy of dose of 50–60 Gy is recommended postoperatively for margin positive cases, for large unresectable tumours and with a history of multiple recurrence.⁸

Learning points.

• We are submitting an extraordinary rare case report of a patient with dermatofibrosarcoma protuberans (DFSP) with solitary pancreatic metastasis.

• This case report highlights the fact that solitary metastasis from DFSP can be managed successfully.

• This would help the readers to get a knowledge of such possibilities and help them in better understanding of the disease and management of the patients.