Poroma and Dermal Duct Tumor


Clinical Photograph of Poroma
Clinical photograph shows a traumatized poroma on the lower back of an adult male, which presented as an irritated polypoid lesion.



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Poroma With Squamoid Features
Low magnification of a poroma with squamoid features shows a basaloid to squamoid-appearing neoplasm with multiple anastomosing connections image between thickened cords of tumor cells and to epidermis. Note the ectatic ductal space on the left image.

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Poroma With Clear Cell Features
Scanning magnification of a poroma with clear cell features shows a basaloid to clear cell image neoplasm with multiple anastomosing connections between thickened cords of tumor cells and to epidermis image.

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Higher Magnification of Clear Cell Poroma
Higher magnification of a clear cell area of poroma shows a proliferation of small cells with abundant pale to clear-staining cytoplasm image and small nuclei lacking atypia.


TERMINOLOGY


Synonyms




• Apocrine poroma

• Eccrine poroma

• Hidroacanthoma simplex (intraepidermal poroma, syringoacanthoma)

• Acrospiroma (older term, includes both poroma and hidradenoma)


Definitions




• Benign adnexal proliferation with anastomosing cords of tumor cells exhibiting ductal differentiation

• Typically has multiple epidermal attachments, except for dermal duct tumor


ETIOLOGY/PATHOGENESIS


Unknown




• Rare cases associated with radiation therapy and pregnancy
image May rarely be multiple (“poromatosis”)

• Formerly considered eccrine, but most cases likely of apocrine differentiation
image May see sebaceous &/or follicular differentiation in apocrine cases


CLINICAL ISSUES


Epidemiology




• Incidence
image Relatively common tumors

• Age
image Usually occur in middle-aged adults

• Sex
image Equal incidence in males and females


Site




• Most common on extremities, especially palmar and plantar surfaces
image May also occur on trunk, head and neck


Presentation




• Solitary pink to reddish papular or nodular lesion
image Minority of cases are pigmented

image Some cases may be very vascular and bleed easily


Natural History




• Stable lesions; do not usually regress


Treatment




• Surgical approaches
image Complete conservative excision is curative

– Typically recommended to prevent recurrence and rare transformation to porocarcinoma


Prognosis




• Excellent; most cases do not show aggressive behavior


MACROSCOPIC


General Features




• Superficial, firm papule or nodule


Size




• Generally < 1 cm but may be larger


MICROSCOPIC


Histologic Features




• Symmetric, well-circumscribed tumor with multiple epidermal attachments
image Intraepidermal component is typically sharply demarcated from adjacent normal epidermis

• Broad, anastomosing columns and thickened cords of tumor cells

• Ductal lumina small, but usually numerous
image A few small cystic structures may also be present

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Apr 24, 2017 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Poroma and Dermal Duct Tumor

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