An Unusual Soft Tissue Tumor of Uncertain Differentiation: a Case Report
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LETTER TO THE EDITOR
An Unusual Soft Tissue Tumor of Uncertain Differentiation: a Case Report Sawan Kumar 1 & Amrita Talwar 1
&
Arvind Ahuja 1
&
Minakshi Bhardwaj 1
Received: 24 June 2020 / Accepted: 19 August 2020 # Indian Association of Surgical Oncology 2020
Sir, Pleomorphic hyalinizing angiectatic tumor (PHAT) is an extremely rare soft tissue tumor of uncertain histogenesis, first described by Smith at al. in 1996 as low-grade neoplasm with close resemblance to neurilemmoma and low-grade malignant fibrous histiocytoma (MFH) [1]. Since its recognition fewer than 100 cases has been reported in the literature so far [2], we report a new case of PHAT in a 50-year-old female who presented with progressively enlarging 8 × 8 cm mass in the left lower leg since 15 years [Fig. 1a]. Imaging revealed a well-defined multilocular lesion with cystic spaces arising from the subcutaneous tissue and abutting the tibia in the anterior leg region, suggestive of benign mesenchymal tumor of soft tissue. The mass was non-tender, painless, soft to cystic in consistency, and not attached to overlying skin or underlying structures. There was no significant past medical or surgical history. Wide local excision of the mass was done. Cut surface showed solid areas which were yellow to brown and firm in consistency, with multiloculated cystic areas [Fig. 1b]. Microscopy revealed a well-circumscribed, however, focally infiltrative tumor, composed of areas of ectatic blood vessels alternating with cellular areas.
* Arvind Ahuja [email protected] Sawan Kumar [email protected] Amrita Talwar [email protected] Minakshi Bhardwaj [email protected] 1
Department of Pathology, ABVIMS & Dr. RML Hospital, New Delhi 110001, India
The vascular areas showed variably sized blood vessels surrounded by hyaline material and cellular areas were composed of markedly pleomorphic oval to polygonal cells, having scant cytoplasm, high N:C ratio, and round to oval nucleus with occasional conspicuous nucleoli. Nuclear lobulation, multinucleation, and nuclear pseudoinculsion were noted in many cells. Intra- and extracellular hemosiderin pigment was also seen [Fig. 1c]. Stroma showed extravasated RBC’s and chronic inflammatory infiltrate. On immunohistochemistry (IHC), tumor cells were strongly positive for CD34 [Fig. 1d] and VEGF [Fig. 1e] and weakly positive for CD99, while negative for CD 68, CD31, and pan CK. Only occasional mitotic figures (< 1/20 hpf) were seen, and Ki-67 labelling index was 1–2%. Based on the characteristic histological features and immunohistochemistry results diagnosis of PHAT was made. PHAT occurs mainly in the fourth to seventh decade with slight female preponderance, typically affecting subcutaneous tissue of lower extremities and clinically simulate hematoma, benign neoplasm, and even Kaposi sarcoma [2]. The most striking histologic feature of PHAT is the hyalinizing angiectatic vasculature. Ultrastructural analysis of the tumor cells shows no recognized feature of mesenchymal differentiation. A primitive fibrobla
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