Poroma represents a group of benign
tumours characterised by monomorphous neoplastic epithelial cells that
show ductal differentiation. This tumour shows histological overlap
with
hidradenoma. Previously some authors have grouped them together
under the term 'acrospiroma'.
Some authors have
subdivided Poroma into:
Three subtypes of poroid neoplasia in a single
lesion: eccrine poroma, hidroacanthoma simplex, and dermal duct tumor.
Histologic, histochemical, and ultrastructural findings.Am
J Dermatopathol. 1994;16(1):66-72.
1.Hidroacanthoma group:
Hidroacanthoma simplex or intraepidermal
poroma (Smith and Coburn 1956) is a form of
poroma in which nests of cells with tubular differentiation are
confined to surface epidermis.
There is no evidence of dermal involvement.
Differential diagnosis: Includes melanocytic neoplasm and clonal seborrheic keratosis.
Differentiation of hidroacanthoma simplex from
clonal seborrheic keratosis-an immunohistochemical study.Am
J Dermatopathol.2004;26(3):188-93.
2. Poroma group: Intraepidermal and dermal
3. Dermal duct tumour - Intradermal lesion. Poroma containing prominent ductal lumina are known as "Dermal ductal tumour."
(Winklemann RK and Mcleod WA 1966).
But the tendency ,
nowadays is to classify all forms as Poroma.
Recent analysis suggests that poromas can be of either eccrine or
apocrine lineage.
Poroma of apocrine lineage are more common.
Clinically presents
as solitary papule or nodule.
Site:
Poromas are usually located on the
hands and feet .
Microscopic features:
Image
Link1
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Image Link2
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Image Link3
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Image Link4
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Well circumscribed lesions composed of small cuboidal epithelial
cells with abundant eosinophilic cytoplasm, monomorphic ovoid nuclei
and inconspicous nucleoli and distinct cytoplasmic margins ;
Cells
are smaller than squamous cells and are connected by intercellular
bridges ; Tumour extends into the dermis as broad columns of cells
from the epidermis ;
Narrow ductal luminas within columns of tumour
cells ; Cytoplasmic vacuolation - intracytoplasmic lumen
formation - within some centrally located tumour cells ;
Occasionally cystic spaces within lobules
of tumour cells ;
Amorphous, eosinophilic material is often present in the cystic spaces
; Backround stroma contains eosinophilic hyalinized collagen and
blood vessels ; Focal sebaceous, pilar and rarely apocrine
differentiation may be identified.
Immunohistochemistry:
Immunopositivity to CEA, specially in the ductal areas.
Cytokeratin is also positive.
IMAGE LINK:(Dr Weems)
Hidroacanthoma Simplex:
CLICK HERE
Poroma:
CLICK HERE
Dermal duct tumour:
CLICK HERE
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