Deep penetrating naevus (plexiform spindle cell naevus/deep penetrating melanocytoma)

Case 412   Jan 2012  (P.McKee) M 11 lower lip 

Wedge shaped infiltrate with heavy pigmentation at bottom.  Mitotic activity almost always seen and atypia common. 

Case 416   Jan 2012 (P. McKee)   F 36 pigmented lesion thigh 

Thought about cellular blue vaevus, but very spindly. Not all views visible, thus can’t see architecture; spindle cells; Spitzoid; some atypia; heavily pigmented lower down. 

Case 1088  25.8.14 (M. Hurt) F 13 arm (*teaching) 

Sometimes called Seab’s naevus (described 1989).  Wedge-shaped or plexiform growth pattern of deeply pigmented spindle or epithelioid cells penetrating deeply.  Little or no junctional component (cf. MM) 

Case 1478  23.2.16 (U. Sundram)  M 73 nose ? blue naevus 

Originally posted as a case from a child.  Solar elastosis alerted commentators to possibility of clerical error. 

Case 1586  25.7.16 (IH Chaudhry)  M 35 pig lesion arm 

Plump oval to spindle cells with heavily pigmented macrophages.  Lack of maturation and a degree of cytological atypia is acceptable.  No mitoses.  These lesions don’t always invade very deeply. 

Case 3069  12.4.22 (U. Sundram) F 11 lesion, cheek 

Dusty cytoplasm, fascicular growth, bland cytology, no mitotic activity.  Confirmed by beta-catenin. 

Case 4099  6.10.22 (S. Taibjee) F 62 right arm ? blue naevus /MM 

Bland cytology with no mitoses.  Beta-catenin strongly +ve in DPN cells (both nuclear and cytoplasmic), whereas the naevo-cellular naevus cells have weaker cytoplasmic staining, sparing the nucleus.  S100 strong+ve, which argues against blue naevus. 

Interesting discussion on the nosology of DPN and Deep Penetrating Melanocytoma. 

Case 4414  21.12.23 (S. Baksh)  M 47 dark brown macule, arm 

Combined tumour showing features of DPN (β-catenin +ve) and congenital naevus. 

Case 4583 27.12.24 (I H Chaudhry) 62F, Right forearm Excision biopsy mole 2 mm margins ?Blue naevus / ?MM