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This common tumor of the skin is most commonly derived from benign eccrine sweat glands. It most commonly presents as a flesh colored bump on the skin, usually in locations where eccrine sweat glands predominate.


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INCIDENCE 1% of primary skin lesions
10% of sweat gland tumors


Sole of the foot 65%
Hair bearing regions 25%
Hand 10%
Head and neck tumors

J Am Acad Dermatol 2001;44:48-52

Ten cases
Not a common location
May be derived from apocrine glands



"Apocrine" poroma: review of the literature and case report.

Kamiya H, Oyama Z, Kitajima Y.

Department of Dermatology, Gifu University School of Medicine, Japan.

J Cutan Pathol 2001 Feb;28(2):101-4 Abstract quote

BACKGROUND: "Apocrine" poroma has recently been proposed as a new term to designate a distinctive benign skin neoplasm with differentiation toward the folliculosebaceous-apocrine unit.

CASE REPORT: In support of alternative differentiation, a case of apocrine poroma is reported in a 73-year-old man. A nodule on the right upper abdomen, which was thought clinically to be seborrheic keratosis or basal cell epithelioma, was excised.

HISTOLOGY: Histologically, this neoplasm heterogeniously consisted of poroma-like, sebaceous and follicular epithelial components. Since these components share the common embryologic origin of the folliculosebaceous-apocrine unit, this histologic pattern indicates apocrine differentiation of the tumor.

CONCLUSION: This is an additional case to support the term "apocrine" poroma as a diagnosis.

Pigmented eccrine poroma occurring on the scalp: derivation of melanocytes in the tumor.

Ohata U, Hara H, Suzuki H.

Department of Dermatology, Nihon University School of Medicine, Tokyo, Japan.

Am J Dermatopathol. 2006 Apr;28(2):138-41. Abstract quote  

We describe a man with a pigmented poroma on the scalp mimicking a pigmented melanocytic nevus.

Histopathological examination showed that melanocytes were mostly distributed at the periphery of the tumor masses.

It is suggested that melanocytes in the tumor masses may have migrated from the adjacent epidermis.

Clear-cell porocarcinoma in situ: a cytologic variant of porocarcinoma in situ.

Rutten A, Requena L, Requena C.

Laboratory of Dermatohistopathology, Friedrichshafen, Germany (A.R.); and Department of Dermatology, Fundacion Jimenez Diaz, Universidad Autonoma, Madrid, Spain(L.R., C.R.).

Am J Dermatopathol 2002 Feb;24(1):67-71 Abstract quote

Poromas are benign neoplasms composed of poroid and cuticular cells. Four histopathologic variants of poromas are accepted, according to the architectural features of the neoplasm: hidroacanthoma simplex or intraepidermal poroma; eccrine poroma, which is a poroma connected to the epidermis that extends to superficial dermis; dermal duct tumor, which develops when the neoplasm is composed of small, solid aggregations of poroid and cuticular cells confined to the dermis with little or no connection with the epidermis; and poroid hidradenoma, which is a solid-cystic, dermal poroma. The malignant counterpart of hidroacanthoma simplex is named malignant hidroacanthoma simplex or porocarcinoma in situ.

This report describes an example of clear-cell malignant hidroacanthoma simplex, a cytologic variant of porocarcinoma in situ, which, to our knowledge, has not been previously reported. In contrast with other clear-cell neoplasms, a relation with diabetes mellitus could not be clearly established in this case.

Sebaceous differentiation in poroid neoplasms: report of 11 cases, including a case of metaplastic carcinoma associated with apocrine poroma (sarcomatoid apocrine porocarcinoma).

Sikl's Department of Pathology, Charles University Medical Faculty Hospital, Pilsen, Czech Republic.

Am J Dermatopathol. 2008 Feb;30(1):21-6. Abstract quote

We describe 11 poroid neoplasms with sebaceous differentiation, including a metaplastic (sarcomatoid) carcinoma arising in association with an apocrine poroma. Six lesions had the silhouette of a classical poroma, 3 of poroid hidradenoma and 1 of dermal duct tumor. In all cases, sebaceous differentiation was identified as clustered or solitary, mature sebocytes occurring mainly at the periphery of intradermal cellular aggregations, accompanied by sebaceous ducts. In one poroma, clusters of sebocytes were seen within intradermal aggregates and intraepidermally. In 1 of the 3 poroid hidradenomas, the eosinophilic cuticle lining the cyst was crenulated in foci associated with sebocytes. In none of the cases were there signs of follicular differentiation. One poroma, in addition to sebaceous differentiation, showed decapitation secretion in some ductular structures. The single carcinoma was an ulcerated oval to spindle cell neoplasm surrounded laterally by the residuum of a poroma containing groups of sebocytes. The epithelial islands of the poroma were prominently keratinized and blended gradually with the pleomorphic cells of the metaplastic carcinoma that immunohistochemically stained focally for cytokeratins and simultaneously showed strong vimentin expression.

Our study supports previous findings that sebaceous differentiation can be identified not only in classical poroma but also in the related lesions known as dermal duct tumor and poroid hidradenoma.

Occurrence of metaplastic carcinoma in association with apocrine poroma is a rare event which indicates the existence of a malignant counterpart of the latter entity, which can be descriptively referred to as "sarcomatoid apocrine porocarcinoma."



P53 Protein Expression in Eccrine Poroma and Porocarcinoma

Taner Akalin, M.D.; Sait en, M.D.; Ayla Yücetürk, M.D.; Gülen Kandilolu, M.D.

Ege University School of Medicine, Department of Pathology, Bornova, Ízmir, Turkey.

Am J Dermatopathol 2001;23:402-406 Abstract quote

The role of p53 mutation has been shown in different human malignancies, including various skin cancers.

In this study, we examined p53 protein expression in 25 eccrine poromas and 11 porocarcinomas by immunohistochemistry. P53 expression was observed in 88% (22 of 25) of eccrine poromas and 73% (8 of 11) of porocarcinomas. In eccrine poromas, percentage of cells reactive for p53 was less than 5% (low expresser) in 6 cases, 5 to 50% (moderate expresser) in 14 and greater than 50% (high expresser) in 2 cases. In terms of intensity, 13 cases showed weak staining, 8 moderate, and 1 case showed strong reactivity. On the other hand, 2 cases of porocarcinoma were low expresser, 2 were moderate and 4 were high expresser. All of the high expressers had also strong staining.

This study has demonstrated that eccrine poromas showed significant p53 expression as much as porocarcinomas and, therefore, p53 positivity cannot be accepted as a valuable parameter for malignancy. P53 gene may involve in the carcinogenetic pathway of porocarcinoma but it is likely that other oncogenes may also have a role.



Porokeratotic eccrine ostial and dermal duct nevus: a case report and review of the literature.

Sassmannshausen J, Bogomilsky J, Chaffins M.

Department of Dermatology, Henry Ford Hospital, Detroit, MI, USA.

J Am Acad Dermatol 2000 Aug;43(2 Pt 2):364-7 Abstract quote

Hamartomas with eccrine differentiation are quite rare. There are 5 accepted classifications: eccrine nevus, eccrine-centered nevus, eccrine angiomatous hamartoma, eccrine syringofibroadenoma, and porokeratotic eccrine ostial and dermal duct nevus. The latter, PEODDN, typically presents as congenital keratotic papules and plaques located on the distal extremities.

We report a classic case of PEODDN that was localized to the left hand since early childhood. The literature on this rare benign tumor is also reviewed.

Metastatic cutaneous carcinoid tumor mimicking an adnexal poroid neoplasm.

Department of Pathology, The George Washington University, Washington, DC, USA.


J Cutan Pathol. 2008 Jan;35(1):54-7. Abstract quote

Objective: Metastatic cutaneous neoplasms may be difficult to differentiate from primary cutaneous neoplasms. Herein, we report an unusual case of metastatic cutaneous carcinoid tumor mimicking an adnexal poroid neoplasm.

Methods: A 53-year-old male man presented with a neoplasm on the vertex of the scalp, clinically resembling a pigmented basal cell carcinoma.

Results: A shave biopsy was suggestive of an apocrine poroma, however, a metastatic carcinoma could not be excluded. After acquiring additional clinical information and the complete excision of the neoplasm, further immunohistochemical stains supported the diagnosis a metastatic carcinoid tumor.

Conclusion: To our knowledge, this is the first case of metastatic carcinoid tumor reported that has mimicked a poroid neoplasm.

Macpherson and Pincus. Clinical Diagnosis and Management by Laboratory Methods. Twentyfirst Edition. WB Saunders. 2006.
Rosai J. Ackerman's Surgical Pathology. Ninth Edition. Mosby 2004.
Sternberg S. Diagnostic Surgical Pathology. Fourth Edition. Lipincott Williams and Wilkins 2004.
Robbins Pathologic Basis of Disease. Seventh Edition. WB Saunders 2005.
DeMay RM. The Art and Science of Cytopathology. Volume 1 and 2. ASCP Press. 1996.
Weedon D. Weedon's Skin Pathology Second Edition. Churchill Livingstone. 2002
Fitzpatrick's Dermatology in General Medicine. 6th Edition. McGraw-Hill. 2003.
Weiss SW and Goldblum JR. Enzinger and Weiss's Soft Tissue Tumors. Fifth Edition. Mosby Elesevier 2008

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Last Updated February 20, 2008

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