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 Dr Sampurna Roy MD

http://www.histopathology-india.net/dermpath.htm

Cysts:

Hydrocystoma -Eccrine/Apocrine

Hamartomas:

Eccrine/Apocrine naevus

Eccrine Angiomatous Hamartoma

Porokeratotic eccrine ostial naevus

Benign Neoplasms:

Syringocystadenoma Papilliferum

Hidradenoma Papilliferum

Nipple Adenoma

Syringoma

Spiradenoma

Cylindroma

Chondroid Syringoma (benign mixed tumour)

Poroma

Hidradenoma

Apocrine adenoma

Papillary eccrine adenoma

Syringofibroadenoma

Distinction between sebaceous adenoma and sebaceoma may be difficult and there is an increasing tendency to regard these two tumours as part of a continuum of benign tumours. Some authors use the term sebaceous adenoma when half or less than 50% of the lesion is composed of germinative and transitional cells, and sebaceoma when greater than 50% of the lesion is composed of germinative and transitional cells.

The term 'sebaceous epithelioma' has been largely discarded by many pathologists as the term 'epithelioma' is confusing & has been used in different ways by various pathologists..

Clinical presentation:  Presents as a solitary circumscribed nodule or an ill-defined plaque. May also present as multiple lesions, specially in Muir-Torre Syndrome.

Site: Located on the face or scalp.

Microscopic features:  

Histologically,  sebaceoma shows irregular shaped cell masses in which more than 50 percent cells are undifferentiated, basaloid cells together with significant aggregates of sebaceous cells and transitional cells. Cysts and duct-like structures contain holocrine secretion and debris.

Rippled-pattern sebaceoma:    Composed of immature sebaceous germinative cells with some foci of advanced sebaceous differentiation. There are small, monomorphous, cigar-shaped basaloid cells in linear rows parallel to one another, resembling the palisading of nuclei of Verocay bodies (rippled-pattern).

In a rare variant of sebaceoma the tumour displayed reticulated and cribriform basaloid epithelial islands.

Some cases show areas resembling seborrheic keratosis.

Image Link (Dr Weems):

Differential Diagnosis:   Sebaceous Carcinoma- some cases of sebaceoma are difficult to differentiate reliably from carcinoma because of the germinative cells (mitotically active and may display atypical nuclear features) ;   Basal cell carcinoma with sebaceous differentiation.

The tumour usually does not recur after excision.

Carcinoid-like pattern in sebaceous neoplasms: another distinctive, previously unrecognized pattern in extraocular sebaceous carcinoma and sebaceoma.Am J Dermatopathol. 2005;27(3):195-203.

Sebaceoma and related neoplasms with sebaceous differentiation: a clinicopathologic study of 30 cases.Am J Dermatopathol. 2002;24(4):294-304.

Rippled-pattern sebaceoma.Am J Dermatopathol. 2001;23(5) :437-43.

Sebaceoma arising in association with seborrheic keratosis. Am J Dermatopathol. 2001;23(1):58-61.

Sebaceous carcinoma, trichoblastoma, and sebaceoma with features of trichoblastoma in nevus sebaceus. Am J  Dermatopathol. 2001;23(5):456-62.

Ductal sebaceoma (sebomatricoma).Pol J Pathol.2000;51(1) :55-7.

Trichoblastoma and sebaceoma in nevus sebaceus. Am J Dermatopathol. 1999 ;21(6):552-6.

Sebaceous neoplasm with reticulated and cribriform features: a rare variant of sebaceoma. J Cutan Pathol. 1998 ;25(4):233-5.

Soft Tissue Pathology; Myxoid Tumours of Soft Tissue ;  Classification of Soft Tissue Tumour;  Gross examination of soft tissue specimen ;  A practical approach to histopathological reporting of soft tissue tumours ;  Grading of soft tissue tumours ; Lipomatous tumours ;Neural tumours ; Myogenic tumours ; Fibroblastic/Myofibroblastic tumours ; Myofibroblastic tumours ;  Fibrohistiocytic tumours ; ChondroOsseous tumours ; Soft TissueTumours of Uncertain Differentiation ; Notochordal Tumour -Chordoma ;Extra-adrenal Paraganglioma ; Gastrointestinal Stromal Tumour ;