CLASSIFICATION OF ADNEXAL TUMOURS OF THE SKIN.pptx

PPT on Adnexal Tumours of the skin

1. ADNEXAL TUMOURS OF THE SKIN Presented by: Dr. Abir Kumar Baruah , 2 nd year PGT Moderator: Prof ( Dr. ) Projnan Saikia , Professor and Head Department of Pathology, Jorhat Medical College and Hospital

2. Skin adnexal tumours (SAT) are a large and diverse group of benign and malignant neoplasms, which exhibit morphological differentiation towards one of the different types of adnexal epithelium present in normal skin: pilosebaceous unit, eccrine and apocrine. Introduction

3. 4 th week: a single‐cell‐thick ectoderm and underlying mesoderm begin to proliferate, and differentiate towards various structures, including skin appendages . Pilosebaceous units: originate from primary epithelial germs in the epidermis Sebaceous glands: budding of sebaceous gland primordium in hair follicle (except labia minora and glans penis) Eccrine glands: from primary epithelial germ cells, but less mesenchymal condensation. Apocrine glands: from an upper bulge in hair follicles that are in the early bulbous peg stage Embryogenesis of normal skin appendages

4. Histology of skin appendages

5. Structure Marker Follicles CK 15, CK 16, CK 17 Sebaceous gland LMWK, EMA, D2-40 Eccrine glands LMWK, EMA, CEA and S100 (HMWK) and cytokeratin (CK) 14 Apocrine Glands gross cystic disease fluid protein 15 (GCDFP‐15) IHC markers of skin adnexa

6. Either from primary epithelial germs, from multipotent stem cells, or from cells of preexistent structures. Appendageal tumours associated with genetic syndromes: from abnormal multipotent stem cells. Multipotent stem cells may manifest more than one differentiation pattern: syringocystadenoma . Histogenesis of adnexal tumours of the skin

7. Hundreds of skin adnexal tumours. Historically classified based on type of differentiation and further subdivided according to a gradient of decreasing differentiation. Problem in this system. Classification of Skin adnexal tumours

8. Tumours with follicular differentiation

9. Clinical: Solitary lesion usually on the face but occasionally on the scalp or neck. Small, skin coloured, dome shaped nodule frequently with a wool like tuft of immature, often white hairs emerging from it. Histopathology: Cystic cavity in dermis lined by squamous epithelium, filled with keratinized material and fragments of hair shafts with small well-differentiated hair follicles radiating from the wall of the cysts. Emanating from the cyst wall, there may be numerous small secondary hair follicles some of which show in addition to a hair and outer root sheath, an inner root sheath with trichohyaline granules. IHC: CK 16, CK 17, CK 15. Trichofolliculoma

10. Same lesion Clinical: 2-4mm yellow-white, smooth, dome-shaped lesions often on the face. Birt -Hogg- Dubé syndrome: Mutation in folliculin gene in chromosome 17p. Multiple fibrofolliculomas along with kidney neoplasms, lung cysts and spontaneous pneumothorax. Histopathology: Fibrofolliculomas : Central distorted hair follicle that is surrounded by a mantle of basophilic, fibrous stroma . Numerous thin anastomosing bands of follicular epithelium extend into this stroma . Trichodiscoma : dermis shows area of fine fibrillary connective tissue containing ectatic blood vessels. Fibrofolliculoma and Trichodiscoma

11. A.k.a. epithelioma adenoides cysticum , multiple benign cystic epithelioma Clinical: solitary or multiple. Numerous rounded, skin coloured, firm papules and nodules, 2-8mm, distributed mainly in the naso -labial folds. Malignant transformation. Histopathology: Superficial dermal, well-circumscribed, small, symmetric. Horn cysts. Tumour islands of basophilic cells, lacelike, adenoid or solid, peripheral palisading. Surrounded by fibroblasts. Differentiation from BCC: CD 10, CK 20. Trichoepithelioma

12. Clinical: 1 cm in size and most commonly on the scalp. Trichoblastic carcinomas, type of BCC. Histopathology: proliferation of follicular germ cells: combination of various proportions of mesenchymal and epithelial cells: trichoblastic fibroma and classic trichoblastoma . Large islands of basaloid tumour cells in the dermis exhibiting peripheral palisading associated with a fibrous stroma . Trichoblastic carcinoma Differentiation from BCC: morphology, Nestin , PHLDA1, laminin-332. Trichoblastoma

13. A.k.a Calcifying epithelioma of Malherbe. Tumour with differentiation towards hair cells, particularly hair cortex cells. Mutations in CTNNB1. gene encoding β -catenin Clinical: Head, neck, upper extremities most common sites. Firm, depp -seated nodule that is covered by normal skin. Associated syndromes: Gardner syndrome, sarcodoisis , skull dysostosis , Rubinstein- Taybi syndrome, Churg -Strauss syndrome, Turner syndrome, Soto syndrome. Histopathology: Tumour is well circumscribed and composed of epithelial islands embedded in a cellular stroma . Two types of cells comprise the islands: basophilic cells and shadow cells. The basophilic cells resemble hair matrix cells. The shadow cells show central unstained shadow at the site of the lost nucleus. In the centre of the field one can see transformation of the basophilic nucleus to shadow cells. Calcium deposition, von kossa staining. Pilomatricoma

14. Clinical: Solitary trichilemmoma , 3-8mm in diameter, normally occurs on the face. Histopathology: The tumour shows verrucous hyperplasia with lobular formations extending into the superficial dermis. As a result of their differentiation towards outer root sheath cells, many cells appear clear, due to glycogen content. The peripheral epithelial cells demonstrate palisading. Epidermoid keratinization. Desmoplastic trichilemmoma : features of trichilemmoma with focal infiltrative growth in the dermis. D/D: verruca vulgaris (special staining with PAS) Multiple trichilemmoma : Cowden syndrome: multiple hamartomas in several organ systems including skin, breast, thyroid, gastrointestinal tract, endometrium and brain: deletion of PTEN gene on chromosome 10. Trichilemmoma

15. Clinical: 85% occur on scalp, remainder on back.. Large, elevated, lobulated mass with ulceration resembling SCC. Rapid enlargement indicates malignant transformation. Histopathology: Irregularly shaped lobules of squamous epithelium undergoing an abrupt change into amorphous keratin. Large pale keratinocytes undergo abrupt keratinization without keratohyaline granules. Low grade malignant proliferating trichilemmal tumour demonstrates irregular infiltration of surrounding dermis. High grade show marked cytological atypia . Differentiation from SCC: AE13 and AE14 staining. Proliferating Trichilemmal tumour

16. Tumours with sebaceous differentiation

17. Clinical: Nearly always occur on the face, chiefly on the forehead and cheeks in the elderly persons. Severely elevated, small soft, yellow, slightly umbilicated papules. Histopathology: Single or multiple enlarged sebaceous gland composed of numerous lobules grouped around a centrally located, wide sebaceous duct. Sebaceous Hyperplasia

18. Clinical: Fordyce spots: groups of minute, yellow, globoid lesions on vermilion border of the lips or on the oral mucosa composed of ectopic sebaceous glands. Montgomery tubercles: ectopic mature sebaceous glands located on the areola of the breast. Histopathology: small, normal, mature sebaceous glands with small ducts. Fordyce Spots and Montgomery tubercles

19. Clinical: yellow, circumscribed nodule located either on the face or scalp. Histopathology: Sharply demarcated from surrounding tissue. It is composed of enlarged sebaceous lobules of varying size and shape. In the lobules, two types of mature cells can be recognized: basaloid and sebaceous cells. Cytological Atypia not seen. Sebaceous Adenoma

20. Clinical: solitary circumscribed nodule or an ill-defined plaque, often yellow in colour . Most lesions on face or scalp. Histopathology: Can range from a well circumscribed nodule to irregularly shaped cell masses in the dermis. More than half of the cells are undifferentiated basaloid cells. Sebaceous epithelioma

21. Clinical: Ocular and extraocular types. Ocular type originates most commonly from meibomian glands and less commonly from glands of Zeis . Extraocular most commonly on head and neck, also vulva and penis. Histopathology: Irregular epithelial lobules associated with epidermal ulceration and infiltrative growth pattern in the dermis. Lesional cells demonstrate marked cytologic atypia , mitotic activity and focal sebaceous differentiation. Sebaceous Carcinoma

22. Combined occurrence of at least one sebaceous skin tumour and one internal malignancy in the same patient. Colon carcinoma is the most common internal malignancy followed by genitourinary tract malignancies. 90% have a germline mutation in the gene that codes MSH-2. Muir-Torre syndrome

23. Tumours with Apocrine Differentiation

24. Clinical: single or multiple, most commonly on scalp and face. Brooke Spiegler syndrome: multiple cyllindromas , spiradenomas and trichoepitheliomas . Histopathology: May manifest both apocrine and eccrine differentiation but apocrine differentiation predominate. The tumour is composed of irregular shaped islands that fit together like pieces of a jigsaw puzzle. The islands are surrounded by a hyaline sheath. Two types of epithelial cells constitute the islands: cells with small dark nuclei representing undifferentiated cells, and cells with large pale nuclei representing cells with certain degree of differentiation towards ductal or secretory cells. Droplets of hyaline material are seen in the islands. Malignant Cylindroma : Islands of cells showing marked nuclear anaplasia and pleomorphism , many atypical mitotic figures, loss of hyaline sheath, loss of palisading at the periphery and invasion into the surrounding tissue. Cylindroma

25. Tumours with Eccrine differentiation

26. Adenoma of intraepidermal eccrine ducts. Clinical: predominantly in women at puberty or later. Usually multiple. Small, skin- coloured or slightly yellow, soft papules usually 1-2mm in diameter. Most common sites are lower eyelids, ckkeks , thigh, axilla. Histopathology: In the dermis, numerous tubular structures are embedded in a dense, collagenous stroma . The walls of the ducts are predominantly lined by two rows of epithelial cells. Some ducts are lined by eosinophilic cuticle, whereas others have comma like tails. Granular eosinophilic material is seen in some ducts. Cytochemistry : Eccrine enzymes such as succinic dehydrogenase, phosphorylase , leucine aminopeptidase . Syringoma

27. Clinical: Common solitary tumour , mst commonly on the sole or sides of the foot, as well as hands and fingers. Histopathology: Broad, anastomosing bands of epithelilal cells emanating from the epidermis. The cells have a uniformly small cuboidal appearance and are connected by intercellular bridges. Eccrine Poroma

28. Clinical: solitary intradermal nodules measuring 1-2cm in diameter. Histopathology: Well circumscribed aggregates of blue tumour cells are seen in the dermis. The epithelial cells are arranged in intertwining bands. Two types of cells can be seen. Cells with small dark nuclei lie at the periphery of the bands; they represent undifferentiated cells. Cells with large pale nuclei lie in the centre of the bands and around small lumina . Collections of hyalinized material seen. Eccrine spiradenoma

29. A.k.a clear cell myoepithelioma , clear cell hidradenoma , eccrine sweat gland adenoma of the clear cell type, solid cystic hidradenoma and eccrine acrospiroma . Clinical: solitary and rarely multiple, can arise in a variety of anatomical sites. Histopathology: Multiple lobules of lesional cells are present in the dermis. Focal cystic change is seen. Cells are clear and polygonal, some of which appear fusiform. Foci of eosinophilic material and ductal lumina are seen. Nodular Hidradenoma

30. A Simple Approach to Adnexal tumours of the skin

31. Lever’s Histopathology of the skin Christopher D.M. Fletcher. Diagnostic Histopathology of Tumours Wheater’s Functional Histology Alhumidi AA. Simple approach to histological diagnosis of common skin adnexal tumors.  Pathology and Laboratory Medicine International . References

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