Acta Derm Venereol 2002; 82: 288–291

CLINICAL REPORT

Long-lasting ``Christmas Tree Rash’’ in an Adolescent: Isotopic Response of Indeterminate Cell in Pityriasis Rosea?

ANDREAS WOLLENBERG, WALTER H. C. BURGDORF, MARTIN SCHALLER and CHRISTIAN SANDER Department of Dermatology and Allergy, Ludwig-Maximilian-University, Munich, Germany

A 13-year-old girl developed a non-pruritic pityriasis rosea, followed by other, smaller red macules on her rosea-like rash, which did not respond to topical cortico- trunk (Fig. 1). After 6 months, all individual lesions steroids or UV therapy but persisted for 2 years. The had persisted, grew slowly in size and became in part lymphohistiocytic inŽ ltrate in the upper dermis showed con uent, but neither itched nor caused any distress. A mononuclear cells immunoreactive with S100, CD68, biopsy showed parakeratosis, extravascular and intraepi- factor XIIIa and CD1a. Electron microscopic evaluation dermal erythrocytes and spongiosis, more suggestive of of these cells demonstrated lamellated dense bodies but pityriasis lichenoides but compatible with pityriasis no Birbeck granules, lipid vacuoles or cholesterol crystals. rosea. Over the following 18 months, the lesions Two diagnoses were made: a primarily clinical diagnosis increased further in number and size. Topical cortico- of generalized eruptive histiocytosis and a more cell- steroids and balneophototherapy were ineVective. biology-based diagnosis of an indeterminate cell histi- At 15 years of age, the patient was admitted to ocytosis. Three years later, the lesions are showing spon- hospital with about 500, round to oval, con uent, taneous resolution, with loss of erythema and  attening. inŽ ltrated, reddish-brown macules and plaques ranging Our patient’s indeterminate cells fulŽ l Rowden’s clas- in size from 5 to 30 mm in a Christmas tree pattern on sical deŽ nition (dendritically shaped epidermal non- the trunk, upper arms and legs (Fig. 2). There was no keratinocytes without identifying cytoplasmic features), lymphadenopathy. Histology now showed a focal as well as Zelger’s newer deŽ nition (cells with features of lymphohistiocytic inŽ ltrate in the upper dermis without both macrophages and dendritic cells). A Christmas tree exocytosis of red blood cells (Fig. 3). The histiocytic pattern has not been previously described in indeterminate cells were immunoreactive with S100, CD68, factor cell histiocytosis. Development of indeterminate cell histi- ocytosis in the lesions of a healing pityriasis rosea might explain the unusual distribution pattern. The development of a skin disorder at the site of an unrelated, already healed skin disease is known as an isotopic response. Key words: indeterminate cell; isotopic response; histiocytosis; pityriasis rosea. (Accepted April 5, 2002.) Acta Derm Venereol 2002; 82: 288–291. Andreas Wollenberg, Department of Dermatology, Ludwig-Maximilians-University , Frauenlobstrasse 9–11, DE-80337 Mu¨ nchen, Germany. E-mail: [email protected]

The classiŽ cation of histiocytic diseases is an elusive and changing Ž eld. This is due to improved methods of investigation and a trend towards cell biological deŽ ni- tions as compared to morphological disease entities. We report the case of a young female with an unusual clinical presentation of cutaneous histiocytosis, and dis- cuss the classiŽ cation of her disease under clinical and cell biological aspects.

CASE REPORT A 13-year-old girl developed a red plaque on her abdo- men suggestive of the herald patch seen in pityriasis Fig. 1. Herald patch on the abdomen with scattered secondary lesions.

Acta Derm Venereol 82 © 2002 Taylor & Francis. ISSN 0001-555 5 Indeterminate cell histiocytosis 289

Fig. 4. Electron microscopy: Several dense and laminated bodies in the cytoplasm of a histiocyte. Absence of Birbeck granula. Bar = 0.2 mm.

pattern of the inŽ ltrates and indeterminate cell histi- ocytosis based on the cell markers and electron micro- scopic Ž ndings (1). Because spontaneous regression is commonly seen in both disease entities, no aggressive treatment regimen was started, but regular follow-up visits were scheduled. Three years later, the lesions are fewer in number and have changed to barely inŽ ltrated reddish macules, indicating an ongoing regression. Fig. 2. Christmas tree rash: multiple round to oval, partly con uent, reddish-brown macules and plaques. DISCUSSION Our patient’s disease is unique, because it may be classiŽ ed on clinical grounds as unusually large lesions of generalized eruptive histiocytosis, in which the distribution pattern followed that of pityriasis rosea, whereas ultrastructural and immunohistochemical data support the diagnosis of indeterminate cell histiocytosis. Generalized eruptive histiocytosis is a clinically deŽ ned disease entity with multiple symmetrical, frequently self- healing, brownish papules preferentially involving the trunk (2). The Ž rst case was reported by Cramer in 1963 (3), while the term generalized eruptive histi- ocytosis was made popular by Winkelmann & Mu¨ller Fig. 3. Biopsy of a persistent papule, showing a superŽ cial perivascular (4). Generalized eruptive histiocytosis is best regarded mononuclear cell inŽ ltrate with modest spongiosis. as an initial stage of many diVerent forms of non- Langerhans’ cell histiocytosis (non-LCH), also classiŽ ed by Zelger et al. as xanthogranuloma s (5). Most patients XIIIa and CD1a, but negative for the Birbeck granule- either resolve spontaneously or show waxing and waning speciŽ c LAG antigen. Giemsa stain showed a slight of lesions. Others may advance to better-deŽ ned entities increase in mast cells, diVusely distributed and not felt such as multicentric reticulohistiocytosis or even xanth- to be abnormal. Electron microscopy revealed that the oma disseminatum. Thus, generalized eruptive histi- inŽ ltrating cells contained lamellated dense bodies but ocytosis is a diagnosis made with caution early in a no Birbeck granules, lipid vacuoles or cholesterol crys- disease course but our patient’s long history and spon- tals (Fig. 4). A thorough clinical and laboratory exam- taneous resolution help seal the diagnosis. A case of ination showed slightly elevated ANA (1:320) and total mimicking generalized eruptive serum IgE (274 kU/l ) but did not reveal any sign of histiocytosis has been described recently (6), but in systemic disease. Caputo’s extensive experience, other patients with gener- Two independent diagnoses seem to Ž t this case – alized eruptive histiocytosis tended to heal, often with generalized eruptive histiocytosis based on the clinical hyperpigmented macules (1).

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Fig. 5. ClassiŽ cation of the histiocytic diseases based on histological, immunohistological and ultrastructural features.

Indeterminate cell histiocytosis is a histologically and and not the Langerhans’ cells are the relevant IgE ultrastructurally deŽ ned disease entity with an inŽ ltrate binding population in atopic dermatitis (14). These of so-called ‘‘indeterminate cells’’ (7, 8). The clinical Ž ndings have recently been extended through functional manifestations range from a solitary nodule at birth (9) investigations (15). to widespread lesions in adults (10). Though only a few DiVerential diagnostic possibilities include Langer- cases have been described, two clinical subtypes seem to hans’ cell histiocytosis (LCH), the other diseases predominate: a solitary nodular form and a multiple included in the spectrum of non-Langerhans’ cell histi- nodular or macular form. In our view, indeterminate ocytosis, mastocytosis and xanthoma (Fig. 5) (16). The cell histiocytosis is not a single disease. Indeterminate histopathological examination excluded the last two cell histiocytosis has also been described as a reactive diagnoses; the lack of Birbeck granules and LAG antigen process. The multiple nodular form is best documented rules out the diagnosis of LCH. Figure 5 shows our as part of nodular scabies, a persistent reaction after view of the classiŽ cation of the histiocytoses, as based acute scabies infestation (11). on the results of the key Ž ndings of Birbeck granules, The classical cell biological deŽ nition of indeterminate CD1a and S100 expression and attempts to arrange the cells is dendritically shaped epidermal non-keratinocyte s historically deŽ ned, clinically meaningful disease entities without identifying cytoplasmic features (melanosomes, by virtue of limited disease features. Merkel cell granules or Birbeck granules) (12). Today, Our patient’s rash started in the distribution pattern many immunobiologists think of indeterminate cells as of pityriasis rosea. A Christmas tree pattern has not truely dendritic, Langerhans’ cell-like cells expressing been previously described in indeterminate cell histi- CD1a and S 100, but lacking Birbeck granules and LAG ocytosis. It is possible that our patient’s indeterminate antigen. In this setting, they may represent a special cell histiocytosis developed in the pre-existing lesions of maturation stage of interstitial type dendritic cells (13). a healing or already healed pityriasis rosea. We Others use this term to describe cells with features of attempted to analyse the inŽ ltrate in the initial biopsy both macrophages and dendritic cells (7). Our patient’s diagnosed as pityriasis lichenoides but there was cells fulŽ l all three of these deŽ nitions. insuYcient tissue remaining for immunohistochemical A minor population of these indeterminate cells is characterization. The development of a skin disorder at found in normal human skin (12). In atopic dermatitis, the site of an unrelated, already healed skin disease is a major population of epidermal dendritic non- known as an isotopic response (17). Development of Langerhans’ cells has been demonstrated by immuno- indeterminate cell histiocytosis in the lesions of a healing phenotypical and ultrastructural analysis, and these pityriasis rosea might explain the unusual distribution so-called in ammatory dendritic epidermal cells (IDEC ) pattern.

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