Pseudosarcomatous Polyp | Dermatopathology

The findings are compatible with a cutaneous pseudo-sarcomatous polyp. The entity was first recognized in 1996 when long-standing polypoid skin lesions with cytologic atypia but a benign clinical course were described. The lesions typically show CD34 and Factor XIIIA positivity. Some authors have postulated that perhaps the pseudo-sarcomatous polyps of the skin represent degenerated dermal spindle cell lipomas. There is a subset of so-called pleomorphic fibromas that likely represent pseudo-sarcomatous fibroepithelial polyps as sometimes the so-called pleomorphic fibromas exhibit a polypoid configuration. The key in recognizing the diagnosis is the bland architecture. These lesions do behave in a benign fashion after local excision.

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Slide 1: 52 year-old man with polypoid shoulder lesions. The excision specimen shows a very large skin tag. The epidermis is fairly unremarkable. The subjacent dermis is composed of a markedly collagenized stroma devoid of adnexal structures.

Slide 2: The epidermis is fairly unremarkable. The subjacent dermis is composed of a markedly collagenized stroma devoid of adnexal structures. A patchy lymphocytic infiltrate is also identified. The lymphocytic infiltrate is most apparent superficially.

Slide 3: ibroblastic elements particularly accentuated immediately beneath the epidermis where a number of stellate cells with multinucleation and hyperchromasia are noted. There are rare atypical mitotic forms. In the depths of the lesion however the atypia is much less. Overall it is accentuated in a subepithelial fashion extending in the deeper aspect of the specimen as well although overall the atypia is less away from the epidermal surface.

Slide 4: In examining the myoid foci, the background matrix appears basophilic and almost chondroid in appearance. The defining cells have a fairly bland spindled appearance.

Slide 5: There is cellular atypia amidst the fibroblastic elements particularly accentuated immediately beneath the epidermis where a number of stellate cells with multinucleation and hyperchromasia are noted..

Slide 6: The features are consistent with the diagnosis of a benign cutaneous pseudo-sarcomatous polyp. The features are consistent with the diagnosis of a benign cutaneous pseudo-sarcomatous polyp.