1. National Specialist Dermatopathology EQA Scheme Circulation A

2. Case A10  Male, 57 years old. Enlarged nodule on lateral aspect of knee. ?Epidermoid cyst.  AE1/AE3, CK20, Chromo, Synapto = positive. CK7, CD99, S100 = negative.  Large fragment of skin, 30 x 40 x 25mm with a nodule to a height of 2.2cm. The cut surface of the nodule is solid and has a gelatinous appearance.

6. Case A10  Most popular diagnosis :  Merkel cell carcinoma 9.96

7. Case A11  Male, 39 years old. ?Histiocytoma excised 1974. Two tender nodules adjacent to scar, growing for 10 years.  CD34 positive.  Skin, 75 x 70 x 10mm with 25 x 10mm scarring and adjacent palpable firm cream nodules, up to 15mm in diameter. Cut section shows firm cream dermal nodules up to 15mm.

13. Case A11  Most popular diagnosis :  DFSP 9.55

14. Case A12  Female, 38 years old. Sentinel lymph node (hot & blue) performed at time of wider excision for desmoplastic melanoma (Breslow thickness 1.5mm).  S100 positive.  Sentinel lymph node.  Lymph node, 20 x 16 x 7mm with blue colouration. (NB - area of interest has been circled on each section)

17. Case A12  Most popular diagnosis :  Benign melanocytic inclusion 7.80

18. Case A13  Female, 40 years old. Tender lesion on right side of upper back present for 15 years.  Raised nodular lesion measuring 0.7cm in diameter.

22. Case A13  Most popular diagnosis :  Eccrine spiradenoma9.88

23. Case A14  Male, 66 years old. Three month history of lesion outer border left lower leg. Started as blood blister and grew rapidly. ?Pyogenic granuloma. Patient refused to have formal excision.  Irregular shaped skin fragment, 15 x 14 x 7mm with unremarkable surface.

28. Case A14  Most popular diagnosis :  Melanoma (+/-balloon cell) 8.89

29. Case A15  Female, 39 years old.  Indurated nodules upper arms with facial rash. Anti DNA Ab-61 iu/ml (0-50)  6mm skin punch biopsy.

34. Case A15  Most popular diagnosis :  Lupus panniculitis 8.79

35. Case A16  Male, 63 years old.  Follicular papules on back.  Skin punch biopsy.

39. Case A16  Most popular diagnosis :  Lichen amyloidosus6.46

40. Case A17  Female, 57 years old. Psoriasis, treated with PUVA. Gets multiple SCC’s. New lesion ?SCC.  AE1/3, EMA, CK5/6, S100, Melan-A = negative. SMA and Desmin = positive.  Skin from leg.  Ellipse of skin, 25 x 17 x 5mm with crusted lesion 8 x 8mm.

45. Case A17  Most popular diagnosis :  Leiomyosarcoma (dermal) 7.52

46. Case A18  Male, 44 years old. Sebaceous cyst with spreading intramuscular infection, abdominal wall. Subsequent previous history – previous chest nodule with overlying soft tissue inflammation including skin involvement.  Skin and soft tissue, 45 x 17 x 15mm

50. Case A18  Most popular diagnosis :  Actinomycosis 5.74

51. Case A19  Male, 60 years old. ?Haemangioma, leiomyoma, angiosarcoma. Present for 15 years.  Skin from left wrist.  Ellipse of skin, 12 x 8 x 4mm.

55. Case A19  Most popular diagnosis :  Glomangioma 6.35

56. Case A20  Male, 71 years old. Skin nodule left upper shoulder ?naevus. ?BCC.  Cytokeratin, SMA, Desmin = positive.  Ellipse 15 x 7 x 3 with pale grey nodule, 9mm in diameter

59.  Leiomyosarcoma.  Cytokeratin positivity recorded.  Ref: Kaddu et al Am J Surg PAth 1997 21(9): 979 - 987

60. Case A21  Female, 50 years old. Pigmented lesion right ear present for 6 months – clinically thought to be a dysplastic naevus.  A 4 x 4 x 4mm punch biopsy of pale skin containing a 2 x 2mm uniformly pigmented papule.

67.  Pigmented trichoepithelioma.  Pigmented trichoepitheliomas exist. Histologically, the main differential is with pigmented basal cell carcinoma but lack of peripheral pallisading & retraction artefact are against it.