Post‐Scabetic Nodules: A Lymphohistiocytic Reaction Rich in Indeterminate Cells

Abstract

We studied six infants and two adult cases of nodular scabies with immunostains and electron microscopy. All eight cases have had either direct (KOH) or family histories of scabies and were treated with lindane 1% cream or permethrin 5% cream. Family members responded very well, but our patients developed multiple papulo-nodular lesions which were initially very pruritic and, in some cases, persisted from several months to over one year. H & E stain of biopsied tissue sections revealed a heavy perivascular and periappendageal lymphohistiocytic cell infiltration. Immunophenotype of these cells was compatible with Langerhans cells, i.e. CD1A (+), S-100 (+) and HLA-DR (+). Electron microscopy showed that these histiocytic cells satisfied all the ultrastructural criteria of Langerhans cells except for the absence of Birbeck's granules. Lag, a monoclonal antibody for Birbeck's granules, was negative. "Persistent nodules in scabies" or "nodular scabies" seems to represent a prolonged response of indeterminate cells-lymphocytes to mite antigens.

Acral, Pure Cutaneous, Self-Healing, Late-Onset, Cellulitis-Like Langerhans Cell Histiocytosis

“…Although CD1a + cells and S-100 + cells had been reportedly seen in nodular scabies, 10 the clinical features and other laboratory reports ruled out this condition in our patient. Further, the lack of CD20 + cells in the nodule and very few in the skin lesions and only a few CD3 + cells in both of these sites point toward the defective antigen presentation capability of the Langerhans cells and confirm an earlier view that the Langerhans cells in LCH are functionally defective.…”

Self-Regressing S100-Negative CD1a-Positive Cutaneous Histiocytosis

“…Interestingly, antigen-dependent indeterminate cell proliferations have previously been reported. 9,10 In conclusion, we present here a case of a selfregressing S100 protein-negative CD1a-positive cutaneous histiocytosis in an adult patient. Very few cases with this immunophenotype have been reported up-to-date, and the classification of these lesions is disputed.…”

Unusual variants of non-Langerhans cell histiocytoses

“…27,28 On the other hand, the development of generalized eruptive ICH at the site of already healed pityriasis rosea has also been described, further suggesting that ICH may occur as a lymphohistiocytic reaction to various antigens. 9 However, in our view, such cases should be regarded as distinct from classic ICH.…”