Site created by

 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

Acquired Melanocytic Naevus

Ancient Naevus

Halo naevus

Balloon cell naevus

Mongolian Spots /Ota's naevus /Ito's naevus

Blue naevus-variants

Deep penetrating naevus  

Combined Naevus

Recurrent naevus

Spitz naevus

Dysplastic naevus

Congenital naevus

Spindle cell naevus

Pigmented melanocytic lesions causing diagnostic problems

Prognostic parameters of melanoma

Lentigo maligna melanoma

Superficial spreading melanoma

Nodular melanoma

Acral lentiginous melanoma

Desmoplastic /Spindle cell /Neurotropic melanoma

Naevoid melanoma

Balloon cell melanoma

Clinical presentation:

A slow growing tumour which shows predilection for sun- exposed hair bearing skin.
Clinically, the tumour presents as a pale tan or reddish papule, indurated plaque or nodule. The tumour size is usually between 0.4 and 2.0 cms.

Sites:    The usual sites include scalp, face, trunk, upper extremities.

Microscopic Images:      
Microscopic features:
Tumour shows  wide range of growth patterns (solid, lobular, trabecular) ; tumour lobules are sharply circumscribed by a hyaline, PAS(+) membrane, and infiltrates with a pushing border ; lobules consist of large tumour cells with PAS reactive and diastase sensitive clear or pale eosinophilic cytoplasm ; stain for mucin is negative ;  foci of pilar-type keratinization and peripheral palisading of cells with subnuclear vacuolization ; some dyskeratotic cells &  numerous mitotic figures  ;  actinic damage ; superficial ulceration; in some cases tumour shows pagetoid spread ; others infiltrate into the deep dermis.

Immunohistochemistry:

Immunocytochemistry reveals positivity for cytokeratin and negativity for CEA and EMA.

Clinical course:
Despite an aggressive growth it has an indolent clinical course. No cases with recurrence or metastasis have been reported in the literature.

Differential diagnosis:

Clear cell carcinomas of the skin.

Benign tumours like trichilemmoma and hidradenoma lack the infiltrative growth pattern and cytological atypia.

Trichilemmal carcinoma and malignant proliferating trichilemmal tumour are two separate entities. The latter, usually arises in a preexisting trichilemmal cyst and has metastatic potential.

Cytokeratin expression in trichilemmal carcinoma suggests differentiation towards follicular infundibulum.In Vivo. 2006 Sep-Oct;20(5):583-5.

Trichilemmal carcinoma: a rare cutaneous malignancy: a report of two cases.Dermatol Surg. 2004;30(1):113-5.

Trichilemmal carcinoma of the upper eyelid.Acta Ophthalmol Scand. 2003;81(5):536-8.

Multiply recurrent trichilemmal carcinoma with perineural invasion and cytokeratin 17 positivity.Dermatol Surg. 2003 ;29(8):886-9.

Trichilemmal carcinoma in an African American.Dermatol Surg. 2002 Mar;28(3):284-6.

Trichilemmal carcinoma developing in a burn scar: a report of two cases.J Dermatol. 1996 Jul;23(7):463-8.

Tricholemmal carcinoma. A clinicopathologic study of 13 cases. Am J Dermatopathol. 1994 Oct;16(5):463-73.

Trichilemmal carcinoma on the thigh: report of a case.J Dermatol. 1994 Jul;21(7):494-6.

Trichilemmal carcinoma: review of 8 cases.J Cutan Pathol. 1993 Feb;20(1):44-9.

Trichilemmal carcinoma occurring in a lesion of solar keratosis.J Dermatol. 1993 Jun;20(6):358-64.

Tricholemmal carcinoma: clinicopathologic study of 10 cases. J Cutan Pathol. 1992;19(2):100-9.

Tricholemmal carcinoma: a study of seven cases.
J Cutan Pathol. 1992;19(2):94-9.