Answer of Dermatopathology Case 24

Poroma


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Abstract:


Poromas and porokeratosis in a patient treated for solid-organ and haematological malignancies. Clin Exp Dermatol. 2009 Dec 2.
We describe a patient with previous solid-organ (testicular, oesophageal) and haematological (acute myeloid leukaemia) malignancies, in whom chronic cutaneous graft-versus-host disease was complicated by poromas and porokeratosis. Chemotherapy, total body irradiation, longstanding immunosuppression and ultraviolet radiation may all have played a part in the pathogenesis of the skin tumours.

Poroma of the hip and buttock.Dermatol Online J. 2009 May 15;15(5):10.
Poroma is a benign adnexal skin tumor seen in middle aged individuals with no sex predilection. The acral sites are the most commonly affected regions. Hip or buttock as a location of origin has rarely been reported. We report two cases of poroma, one located on the hip of a 75-year-old man and the other on the buttock of a 60-year-old man.

New concepts on the histogenesis of eccrine neoplasia from keratin expression in the normal eccrine gland, syringoma and poroma.Br J Dermatol. 2008 Sep;159(3):633-45. Epub 2008 Jul 19.
BACKGROUND: Peripheral and luminal layers of eccrine sweat gland ducts are self-renewing structures. Proliferation is restricted to the lowermost luminal layer, but randomly scattered in the peripheral layer. Each layer exhibits differential expression of keratins K5/K14 and K6/K16. Keratin K1 occurs only in peripheral cells and the novel keratin K77 is specific for luminal cells. OBJECTIVES: To investigate the expression of luminal (K77), peripheral (K1) and further discriminatory keratins in two eccrine sweat gland tumours: syringoma,thought to show differentiation towards luminal cells of intraepidermal sweat ducts and eccrine poroma, considered to arise from poroid cells, i.e. peripheral duct cells; and keratinocytes of the lower acrosyringium/sweat duct ridge differentiating towards cells of intradermal/intraepidermal duct segments. METHODS: Paraffin-embedded sections were examined by immunohistochemistry using several keratin, smooth muscle actin and Ki-67 antibodies. RESULTS: We confirmed the ductal nature of syringomas. Despite drastic morphological alterations inboth layers, their keratin patterns remained almost undisturbed compared with normal ducts. In eccrine poroma epidermal keratins K5/K14 were ubiquitously expressed in all poroid cells. Cell islands deviating morphologically from poroid cells contained epidermal keratins K1/K10. K77 expression was limited to luminal cells of intact duct structures within the tumours. CONCLUSIONS: Syringomas are benign tumours of luminal cells of the lower most intraglandular sweat duct. Poroid precursor cells of poromas do not comprise peripheral duct cells nor do poromas differentiate towards peripheral or luminal duct cells. Instead, poroid cells consist only of keratinocytes of the lower most acrosyringium and the sweat duct ridge and poromas tend to differentiate towards the cells of the upper acrosyringium.

A single lesion showing features of pigmented eccrine poroma and poroid hidradenoma. J Cutan Pathol. 2008 Sep;35(9):861-5. Epub 2008 Apr 17.
Poroid hidradenoma (PH) is a variant of poroma. This entity was defined by Abenoza and Ackerman in 1990. This neoplasm shows architectural characteristics of hidradenoma (tumor cells confined entirely within the dermis in both solid and cystic components) and cytologic characteristics of poroid neoplasm (poroid and cuticular cells, the latter showing ductal differentiation). We herein document a case of single poroid lesion with the features of both eccrine poroma and PH. The patient was a 55-year-old woman with a pigmented nodular lesion on her upper back for 7 years. The histopathologic features of the lesion were consistent with those of eccrine poroma and PH. Unlike most eccrine poromas, this case was pigmented, clinically and microscopically.