Blue naevus, cellular form

Case 486  April 2012 (P. McKee)  M 40 mass buttock – cellular form  

Many thought this was malignant, such as clear cell sarcoma or melanoma.  However, observed mitotic activity is to be expected in this form of blue naevus and there was no significant pleomorphism. 

DD: clear cell sarcoma, which would be S100 +ve. 

Case 768   28.5.13  (IH Chaudhry)  M 74 long-standing lesion on buttock 

Atrophic cellular BN.  Difficult on only two HP views.  “Cell ball” pattern. 

Ref: Rodriguez HA, Ackerman LV. Cellular blue nevus. Clinicopathologic study of forty-five cases. Cancer. 1968 Mar;21(3):393-405. PubMed PMID: 5637949. 

Case 1122  10.10.14 (R.Carr)  F 22 buttock lump  - cellular form (*teaching) 

Vertically orientated expansile dermal nodule.  Adnexae preserved (not shown).  Slight nuclear atypia and mitoses.  S100-ve – this can be seen in common and cellular blue naevi. 

Case 1284   26.5.15 (U. Sundram)  F 55 foot 

Also a small intradermal naevus present, so a “true and blue”. 

Case 1610  22.8.16 (IH Chaudhry)  55 scalp, previous MM elsewhere 

Fusiform area of heavy melanin pigmentation in upper dermis obscuring cellular detail but with preservation of surrounding structures.  Bleaching revealed cellular (epithelioid) BN. 

DD: tumoral melanosis 

Case 2066 8.5.18  (U. Sundram)  M 36 pigmented nodule ankle 

Completely intradermal.  Some vestiges of i-d naevus but main lesion is heavily pigmented spindle cell lesion. Sclerotic entrapment of melanocytic nests is a pattern often seen in CBN with ancient change. 

DD: PEM/epithelioid BN, and epithelioid melanoma 

Case 2079  25.5.18  (R. Carr)  F 75 arm 

Heavily pigmented dermal tumour.  Epithelioid BN (called PEM if part of Carney complex). 

Ref: Yazdan P1, Haghighat Z, Guitart J, Gerami P. Epithelioid and fusiform blue nevus of chronically sun-damaged skin, an entity distinct from the epithelioid blue nevus of the Carney complex. Am J Surg Pathol. 2013 Jan;37(1):81-8. 

Case 2124  31.7.18 (U. Sundram)  F 65 forehead.  Cellular variety.  Concerns expressed about the possibility of overlying epidermal melanocytic proliferation.  Comment on: Yazdan P, Haghighat Z, Guitart J, Gerami P. Am J Surg Pathol. 2013 Jan;37(1):81-8 

Case 2644  25.8.20 (U. Sundram)  M 84 shoulder 

I thought this was a deep penetrating naevus because of its silhouette .     

Case 3007  14.1.22 (R.Carr) F 15 yellow, firm dermal lump back of hand 

Location and age typical for blue naevus.  Bulbous downgrowths, nesting, giant cells and preservation of adnexal structures typical, as is strong MelanA + and S100 -ve. 

DD: clear cell sarcoma – would have expected focal MelanA+ve and S100 +ve. 

Plexiform fibrohistiocytic tumour. 

Case 4205  3.323 (IH Chaudhury)  F 52 Deeply pigmented blue naevus hairline 

Case 4453 14.2.24 (H. Diwan) M 58 scalp lesion