Prurigo nodularis is an
uncommon lesion that presents
as extremely pruritic nodules with a wide anatomical distribution but
particularly on extensor aspects of limbs.
Often lesions are
multiple but solitary nodules can occasionally occur.
Lesions tend to be
symmetrical and are associated with excoriations.
Females are more
often affected than males.
consider this condition as part of the spectrum of lichen simplex.
mycobacteria may be a contributing factor in prurigo nodularis.
reveals psoriasiform hyperplasia or pseudo-epitheliomatous hyperplasia
hyperkeratosis with hypergranulosis and focal parakeratosis ;
spongiosis and exocytosis of mononuclear cells;
formation in association with changes of excoriation (fibrin deposition and
cellular debris) ;
hyperplasia of hair follicles;
Mild fibosis of
papillary and superficial dermis and telangiectasia ;
Mild to moderate
perivascular mononuclear inflammatory cell infiltrate composed of
lymphocytes, histiocytes and plasma cells ;
Nerve hyperplasia as
reported in the past is not usually a feature.
is not difficult if the biopsy is big enough.
In small biopsies differential
other causes of pseudo-epitheliomatous hyperplasia.
: This is a benign pathological reaction pattern, histologically
characterized by bulbous thickening of squamous epithelium (follicular
infundibula and acrosyringium).
There is abrupt transition beween
lesion and adjacent epidermis. The cells have abundant often glassy
Pseudoepitheliomatous hyperplasia is seen in the following conditions:
Chronic irritation ; skin trauma ; dermal inflammatory processes
like chromomycosis ;
Prurigo nodularis ;
Granuloma fissuratum and
in associatiation with
chondrodermatitis nodularis helicis ; Spitz
melanoma, overlying granular cell tumour and cutaneous T cell tumour .