Pityriasis rotunda

Question 1

Describe

Answer 1

Well demarcated, thin hyperpigmented plaques with fine scale

Question 2

What is Pityriasis Rotunda?

Answer 2

Assymptomatic dermatoses

Primarily seen in the far east / mediterraneous basin / indivudals of african descent

Characterised by large circular and ploycyclic scaly pathces with sharp margins that are typically hyperpigmented > hypopigmented

Localised to ther trunk and proximal extremities

Question 3

Clinical features of Pit Rotunda

Answer 3

asymptomatic

large circular and polycyclic lesions
* often 10 cm (but may be up
to 30 cm) in diameter
* fine scale
* moderately hyperpigmented
* sharp margin
* no inflammation.

The trunk and extremities are favored.

A hypopigmented halo has been described in some patients

sometimes the entire lesion
can be hypopigmented.

Question 4

What are the histo findings of Pit Rotunda?

Answer 4

Same as ichthyosis vulgaris
* absent or diminished granular cell layer
* moderate hyperkeratosis
* without parakeratosis

Plus
* Increased pigmentation of the basal cell layer
* pigment incontinence
* perivascular lymphohistiocytic infiltrate
* follicular plugging may also be observed.

Special stains for fungi are
negative

Question 5

What is the DDx for Pit Rotunda?

Answer 5

Tinea corporis
Tinea veriscolour
MF
Leprosy

Question 6

How do you treat pityriasis rotunda?

Answer 6

Very difficult

Topical lactic
acid, urea, tars, emollients, and corticosteroids have **provided little
benefit. **

Topical tretinoin cream can result in modest improvement

systemic retinoids warrant consideration for patients with more
extensive disease.

Spontaneous remission is possible