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Pathology of Deep Penetrating Nevus

"A benign pigmented tumour which should

not be mistaken for melanoma".

Dr Sampurna Roy MD     

Dermatopathology Quiz Case 137

Diagnosis: Deep Penetrating Nevus





Deep penetrating nevus is a distinct form of melanocytic nevus and may mimic various pigmented lesions.

This lesion has distinct microscopic features which helps in excluding melanoma and establishing the correct diagnosis.

Clinically, the lesion usually occurs on the head and neck region and presents as darkly pigmented papule or nodule.

Many authors regard this lesion as a variant of blue nevus.    

Microscopic features:


The lesion has a wedge shaped contour and extends deep into the dermis and may even  reach the subcutis.

It is usually compound in type and consists of plump epithelioid cells and spindle cells.

The melanocytes may display irregular size and shape and the cells do not diminish in size at the base of the lesion. 

The cells surround hair follicle, sweat glands and nerves.

Pilar muscles are some times infiltrated.

There is low mitotic activity. 

No atypical mitotic figures are present.  


The most important differential diagnosis is Melanoma.

The following features helps in establishing the diagnosis:

1.  Melanoma of the thickness of deep penetrating nevus usually displays  marked cellular and architectural atypia.

2.  In deep penetrating nevus there is no pagetoid intraepidermal spread. 

3.  There is no irregular epidermal acanthosis or thinning.

4.  No irregular fibroinflammatory dermal response is seen in deep penetrating nevus.

5.  Proliferating cell nuclear antigen (PCNA) is present in scattered melanocytes (less than 5%) in the deep penetrating nevus.

In melanoma 25%-75% cells show immunopositivity with PCNA.

The differential diagnosis also include Spitz nevus ; congenital melanocytic nevus.            

Further reading:

Deep penetrating nevus: a case report and brief literature review.

Deep penetrating (plexiform spindle cell) nevus

Linear arrangement of multiple deep penetrating nevi: report of first case and review of literature

Proliferating cell nuclear antigen staining in deep-penetrating nevi

Deep penetrating nevus: a review

An unconventional deep penetrating melanocytic nevus with microscopic involvement of regional lymph nodes

Deep penetrating (plexiform spindle cell) nevus. A frequent participant in combined nevus.

Deep penetrating nevus.





Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)






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