Tuesday, 24 January 2012

Types of halo naevi



                                                                                               
Type of halo naevus (5 types)
Features
1. Classic halo naevus with histopathologically apparent inflammation (the infiltrate contains many cytotoxic T-cells, and may represent immunologically-induced rejection).
The classic lesion is a brown naevus with a surrounding halo of vitiligo-like depigmentation. The naevus usually undergoes involution (losing its pigment then disappears) and the halo usually repigments.


In unusual lesionsdarkening of the naevus rather than lightening has been described (? postinflammatory hyperpigmentation).
2. Halo naevus with no histopathologically apparent inflammation.
In such instances,
the naevus does not undergo involution.
3. Halo naevus without halo
It is actually without a clinical halo but with histopathologically apparent inflammation. The naevus may or may not undergo involution.  
4. Inverse halo naevus*
It is actually a centrifugal dissolving naevus (a centrifugal destruction of melanocytes producing clinically an annular naevoid ring).
5. Pseudo-halo naevus
It is merely produced by the application of sunscreen to a naevus and its immediate surround.



Circulating antibodies that react against melanoma cells have been found in a high proportion of individuals with halo naevi, as have circulating lymphocytes with an activated phenotype, suggesting that both humoral and cell-mediated immunity are involved in the rejection of naevus cells and the formation of the halo. Interestingly, fibrosis does not occur in the dermis as a consequence of the halo naevus regression, whereas it does occur in regressing melanomas. This difference may result from the higher expression of the antifibrotic cytokine tumour necrosis factor-ɑ (TNF-ɑ) in halo naevi than in regressing melanomas. Tocilizumab may lead to the development of halo naevi secondary to activation of the adaptive immune system or because of the direct inhibitory effects of increased serum IL-6 levels on melanocytes and their function**.


A full mucocutaneous examination at the time of diagnosis is indicated to exclude a concurrent melanoma. The decision to remove the naevus at the centre of the halo is based on its morphologic features, just as with any other naevus. Not infrequently, halo naevi are multiple, occurring either simultaneously or successively. There may be associated vitiligo and/or Turner’s syndrome. Note that halo dermatitis around a melanocytic naevus is called Meyerson’s naevus and it usually resolves spontaneously within a few months, without involution of the naevus. This differs from halo naevus (also called Sutton’s naevus), although the two conditions have been reported to coexist in the same patient, and progression to Sutton’s naevus has occurred. 




* Nashan D, Meiss F, Braun-Falco M, Hofbauer M, Hofmann S. Multiple target-like pigmented nevi: an inverse halo-nevus phenomenon. J Eur Acad Dermatol Venereol 2010; 24: 104–105.
** Kuet K, Goodfield M. Multiple halo naevi associated with tocilizumab. Clinical and Experimental Dermatology 2014 (Early view). 





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Main Works of Reference List (The first eight are my top favourites)

  • British National Formulary
  • British National Formulary for Children
  • Guidelines (BAD - BASHH - BHIVA - Uroweb)
  • Oxford Handbook of Genitourinary Medicine, HIV, and Sexual Health
  • Oxford Handbook of Medical Dermatology
  • Rook's Textbook of Dermatology
  • Simple Skin Surgery
  • Weedon's Skin Pathology
  • A Concise Atlas of Dermatopathology (P Mckee)
  • Ackerman's Resolving Quandaries in Dermatology, Pathology and Dermatopathology
  • Andrews' Diseases of the Skin
  • Andrology (Nieschlag E FRCP, Behre M and Nieschlag S)
  • Bailey and Love's Short Practice of Surgery
  • Davidson's Essentials of Medicine
  • Davidson's Principles and Practice of Medicine
  • Fitzpatrick's Colour Atlas and Synopsis of Clinical Dermatology (Klaus Wolff FRCP and Richard Allen Johnson)
  • Fitzpatrick’s Dermatology in General Medicine
  • Ganong's Review of Medical Physiology
  • Gray's Anatomy
  • Hamilton Bailey's Demonstrations of Physical Signs in Clinical Surgery
  • Hutchison's Clinical Methods
  • Lever's Histopathology of the Skin
  • Lever's Histopathology of the Skin (Atlas and Synopsis)
  • Macleod's Clinical Examination
  • Martindale: The Complete Drug Reference
  • Oxford Handbook of Clinical Examination and Practical Skills
  • Oxford Textbook of Medicine
  • Practical Dermatopathology (R Rapini)
  • Sexually Transmitted Diseases (Holmes K et al)
  • Statistics in Clinical Practice (D Coggon FRCP)
  • Stockley's Drug Interactions
  • Treatment of Skin Disease: Comprehensive Therapeutic Strategies
  • Yen & Jaffe's Reproductive Endocrinology