DERMAL DUCT TUMOR
This tumor is composed of the same kind of epithelium that is found in
Pinkus' eccrine poroma1, but prominent
epidermal connections of the type characteristic of eccrine poroma are
not present. The nests of tumor have smooth outer borders, and they are
composed of a relatively uniform population of small epithelial cells.
Most of the cells are round or oval, but spindle cells can be focally present.
Cells having squamous characteristics are seen around foci of duct differentiation.
These cells (in dermal duct tumors as well as in the other acrospiromas)
have visible cytoplasm in contrast with the inconspicuous or invisible
cytoplasm (other than in foci of duct differentiation) found in spiradenomas
and cylindromas. There is a form of parakeratosis within tumor nests that
has been referred to as 'necrosis en masse' in some dermal duct tumors
and poromas. Mitoses, in the absence of atypia or infiltrative patterns,
are not indicative of malignancy.
Note regarding terminology: The dermal duct tumor2, originally
described by Winkelmann and McLeod, was meant to be included with the eccrine
acrospiromas3 as described by Johnson and Helwig. They stated,
with regard to the dermal duct tumor, "-----we believe this is not a separate
entity but just one of the variations
of the acrospiroma." They also included Pinkus' poroma as well as the
clear cell hidradenoma. The clear cell hidradenoma is equated exclusively
with the term 'acrospiroma' in some texts for reasons that are a mystery
to me.
 |
Scan power showing tumor nests having rounded, smooth
outer borders, and these tumor nests are restricted to the dermis. |
 |
Low power view showing two tumor nests. |
 |
High power of 'necrosis en masse' (large nuclear
remnants resembling parakeratosis) |
 |
High power showing duct differentiation. This usually
is not prominent in these tumors. |
 |
High power showing a mitosis (MIT). This is of no
significance in this background. |
References:
1. Pinkus et al, Arch Dermatol 74:511-521, 1956
2. Winkelmann RK, McLeod WA, Arch Dermatol 94:50-55, 1966
3. Johnson BL Jr, Helwig EB, Cancer 23:641-657, 1969
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