Paraneoplastic Autoimmune Multi

CORRESPONDENCE LINK TO ORIGINAL ARTICLE LINK TO AUTHORS’ REPLY

BO remains unclear. Indeed, sloughing of bronchial epithelial cells can contribute to Paraneoplastic autoimmune multi- occlusion of the small airways, providing a potential mechanism for the respiratory fail- organ syndrome is a distinct entity ure in patients with PNP6. Finally, metaplasia is not typically observed in autoimmune from traditional pemphigus subtypes conditions but is a feature of precancerous or cancer pathology, which may account for the over-representation of Castleman disease in Kyle T. Amber patients with PNP and BO13. I commend the authors of the Primer on pem- supporting the notion that PNP is an unre- Kyle T. Amber phigus (Pemphigus. Nat. Rev. Dis. Primers 3, lated condition. The cutaneous manifestations Department of Dermatology, University of California 17026 (2017))1 for their detailed review of of pemphigus subtypes frequently involve the Irvine Health, Irvine, CA, USA. this disease, which is an excellent and highly scalp and usually do not present on palms and e-mail: [email protected] defined model to study human autoimmun- soles, whereas, as the authors note, in PNP doi:10.1038/nrdp.2018.12 ity. In the Primer, the authors included para- there is “involvement of palms and soles but Published online 22 Feb 2018 neoplastic pemphigus (PNP) as a subtype not the scalp.” Indeed, the involvement of the 1. Kasperkiewicz, M. et al. Pemphigus. Nat. Rev. Dis. of pemphigus; however, it should be noted palms and soles is common in pemphigoid Primers 3, 17026 (2017). 2. Anhalt, G. J. et al. Paraneoplastic pemphigus. An 7 that a different classification of PNP has diseases . When PNP affects the oral mucosa, autoimmune mucocutaneous disease associated with been described, based on differences in the the PNP is far more diffuse and severe than neoplasia. N. Engl. J. Med. 323, 1729–1735 (1990). 3. Frew, J. W. & Murrell, D. F. Paraneoplastic underlying pathophysiological mechanisms. that observed in pemphigus vulgaris, resulting pemphigus (paraneoplastic autoimmune multiorgan The term PNP was coined after identifying in erosive stomatitis8. syndrome): clinical presentations and pathogenesis. Dermatol. Clin. 29, 419–425 (2011). shared serological immunopathological fea- In marked contrast to pemphigus vulgaris 4. Mimouni, D. et al. Paraneoplastic pemphigus tures with pemphigus2. Clinically, PNP has and pemphigus foliaceus, in which mortal- in children and adolescents. Br. J. Dermatol. 147, 725–732 (2002). 9 a wide spectrum of morphological presen- ity does not exceed 10% , a fatal outcome is 5. Fang, Y. et al. A critical role of surgery in the treatment tations: it can mimic erythema multiforme, observed in 90% of patients with PNP10. The for paraneoplastic pemphigus caused by localized Castleman’s disease. Med. Oncol. 27, 907–911 (2010). lichen planus pemphigoides, bullous pem- authors of the Primer state that this mortality 6. Nguyen, V. T. et al. Classification, clinical phigoid, graft-versus-host disease or pem- could be due to underlying malignancy, infec- manifestations, and immunopathological mechanisms 3 of the epithelial variant of paraneoplastic autoimmune phigus . In fact, a lichenoid presentation has tion or bronchiolitis obliterans (BO), which multiorgan syndrome: a reappraisal of paraneoplastic more commonly been described than a pem- could result from fibrotic changes in the bron- pemphigus. Arch. Dermatol. 137, 193–206 (2001). 4 + 7. Schmidt, E. & Zillikens, D. Pemphigoid diseases. phigus presentation . Furthermore, the clini- chioles induced by desmoglein 3‑specific CD4 Lancet 381, 320–332 (2013). cal course of PNP can be distinct from that T cells that target desmoglein 3‑expressing 8. Czernik, A., Camilleri, M., Pittelkow, M. R. 11 & Grando, S. A. Paraneoplastic autoimmune of other pemphigus subtypes like pemphigus cells in squamous metaplasia in the lung . multiorgan syndrome: 20 years after. Int. J. Dermatol. vulgaris or pemphigus foliaceus. For exam- However, although metaplasia is found in 50, 905–914 (2011). 9. Kridin, K., Zelber-Sagi, S. & Bergman, R. Mortality ple, PNP does not always respond to treat- the affected pulmonary epithelial lining of and cause of death in patients with pemphigus. ments that usually resolve pemphigus, the patients with PNP with pulmonary involve- Acta Derm. Venereol. 97, 607–611 (2017). 10. Nousari, H. C. et al. The mechanism of respiratory spectrum of autoantibodies in patients with ment, metaplastic human bronchial epithelia failure in paraneoplastic pemphigus. N. Engl. J. Med. PNP is different from that observed in pem- do not express desmoglein 39. Thus, fibrosis 340, 1406–1410 (1999). 11. Hata, T. et al. Ectopic expression of epidermal phigus vulgaris or pemphigus foliaceus with and BO are probably mediated by T cells and antigens renders the lung a target organ in the presence of non-skin autoantibodies, and autoantibodies against epiplakin, which is paraneoplastic pemphigus. J. Immunol. 191, 83–90 6,12 (2013). PNP by definition is associated with malig- expressed by human pulmonary epithelia . 12. Tsuchisaka, A. et al. Epiplakin is a paraneoplastic nancy or Castleman disease. For example, in Similarly, fibrosis is not the hallmark of pemphigus autoantigen and related to bronchiolitis obliterans in Japanese patients. J. Invest. Dermatol. patients with Castleman disease and a PNP pemphigus vulgaris or pemphigus folia- 136, 399–408 (2016). phenotype, removal of the tumours resulted ceus. The presence of anti‑desmoglein 3 13. Lee, J., Bloom, R. & Amber, K. T. A systematic review 5 of patients with mucocutaneous and respiratory in the resolution of PNP . Thus, PNP would autoantibody-induced pulmonary fibrosis complications in paraneoplastic autoimmune be more appropriately considered a single in mice is not consistent with humans with multiorgan syndrome: Castleman’s disease is the predominant malignancy. Lung 193, 593–596 (2015). pemphigus-like mucocutaneous phenotype pemphigus vulgaris, who do not develop pul- of paraneoplastic autoimmune multi-organ monary fibrosis. As desmoglein 3 is present at Competing interests The author declares no competing interests. syndrome (PAMS)6. Here, I present some other sites, namely the oesophagus, pharynx, evidence supporting this classification. anal canal and vagina, it is unclear why fibrosis How to cite this article Amber, K.T. Paraneoplastic autoimmune multi-organ syndrome Clinically, PNP has many distinctions from in patients with PNP only occurs in the lung. is a distinct entity from traditional pemphigus subtypes. pemphigus vulgaris and pemphigus foliaceus, Whether lung-specific metaplasia precipitates Nat. Rev. Dis. Primers. 4, 18012 (2018).