|Year : 2000 | Volume
| Issue : 5 | Page : 244-246
Pityriasis rosea: A histopathologic study
D Prasad, RR Mittal, RLS Walia, R Popli
The histopathologic features of pityriasis rosea (PR) have been considered by many authors to be compatible with those of dermatitis, but it is not surprising that histological difference may exist between PR and dermatitis. fifty patients of pityriasis rosea were included in this study. We studied the 50 biopsies including 9 biopsies from herald patches. The characteristic features were; absence or decrease of the granular cell layer, extravasation of red blood cells in papillary dermis and partly into the epidermis, dyskeratosis, liquefaction of basal cells, homogenization of papillary collagen, intraepidermal vesicles in apparently dry skin. In addition of these features, we observed prominent delling of epidermis and a typical spongiotic pattern not reported earlier. The biopsies from herald patches showed minor differences from the secondary lesions. We also compared the histopathological features of recent lesions with older lesions.
Keywords: Pityriasis rosea, Histopathologic study
|How to cite this article:|
Prasad D, Mittal R R, Walia R, Popli R. Pityriasis rosea: A histopathologic study. Indian J Dermatol Venereol Leprol 2000;66:244-6
|How to cite this URL:|
Prasad D, Mittal R R, Walia R, Popli R. Pityriasis rosea: A histopathologic study. Indian J Dermatol Venereol Leprol [serial online] 2000 [cited 2014 Nov 21];66:244-6. Available from: http://www.ijdvl.com/text.asp?2000/66/5/244/4934
| Introduction|| |
Histopathology of pityriasis rosea (PR) was first described by Unna in 1894.  He reported that majority of biopsies showed eczematoid pattern. The microscopic features of PR have been considered to be compatible with those of so called dermatitis, but for diagnosis of PR, the additional histopathological features specially in combination are of great value. The absence or decrease of the granular layer, often without concomitant parakeratosis, was first described by Lowenbach in 1899  and later by Solo.  The extravasation of red blood cells into the papillary dermis and partly into the epidermis, was pointed out first by Sabourav, later by Bunch and Tilley.  Similarly Okamato  et al reported extravasation of erythrocytes in 66% of biopsies. Panizon and Block  based on the examination of 62 biopsies from PR patients, discussed frequency and intensity of 31 histological criteria. They mentioned four characteristic histological findings, eczematoid pattern (Unna's sign), absence or decrease of granular cell layer (Lowenbach's sign), erythrocytes in the papillary dermis and partly into the epidermis (Sabouraud's sign) and homogenisation of papillary collagen. Recently it has been demonstrated with scanning electron microscopy that parakeratotic cells in PR showed specific surface patterns (print) and looked like semicrystalloid.  Drago et al on electron microscopic investigations and polymerase chain reaction in mononuclear cells, plasma and skin in PR concluded that it is a clinical presentation of HHV-7 reactivation. 
| Materials and Methods|| |
Fifty cases of PR were included in the study. In every case a detailed clinical history was taken, complete general and systemic examination was done to establish the presence or absence of any other associated diseases. Routine investigations included hemogram, urinalysis and STS. Skin biopsy for histopathological study was taken in all the patients. Nine biopsies were taken from active herald patches.
| Results|| |
The epidermal changes in 50 patients of PR are shown in [Table - 1]. Delling i.e. depression in surface of epidermis was seen in 39 biopsies. These valleys or depressions were filled with keratin and pinkish exudates. Irregular or regular splits in epidermis with transepidermal elimination of pinkish exudates was seen.
Dermal changes are shown in [Table - 2].
The histopathologic features of biopsies taken from herald patients are shown in [Table - 3]. We also compared the histopathologic findings in recent lesions and old lesions. The mean duration of lesions was calculated which was 7.6 days for recent lesions and 18.2 days for older lesions. Comparing the two groups it was found that dyskeratosis (86.5%), decrease in granular layer (9.3%) and hydropic degeneration of basal cells (86.4%) were more common in recent lesions. The main difference observed was presence of eosinophils in inflammatory infiltrate in papillary dermis in older lesions with no eosinophils in recent lesions.
| Discussion|| |
The histopathologic features of PR have been considered by many authors to be compatible with those of dermatitis. For the diagnosis of PR, we consider that additional histopathological features specially in combination are of great value.
These additional features are: absence or decrease of the granular cell layer, extravasation of red blood cells in papillary dermis and partly into the epidermis, dyskeratosis, liquefaction degeneration of basal cells, homogenization of papillary collagen, and intraepidermal vesicles in apparently dry skin. All these features were observed in the majority of biopsies [Table - 1] & [Table - 2]. In addition to these features, we observed prominent delling of epidermis and a typical spongiotic pattern not reported earlier. Delling (depression of surface epidermis not related to opening of sweat duct or pilosebaceous duct) was seen in 39 biopsies. The delling has been reported in SLE and lichen sclerosis et atrophicus. We observed spongiosis in all cases and a typical spongiotic pattern in epidermis with linear splits in epidermis. In the present study, we also studied the histopathologic features of herald patch. There is only one study in literature which compared the histological findings in herald patch and secondary eruption. This study by Oakamoto et al  showed that there are only minor differences between the two. We showed that hyperkeratosis, acanthosis, pappillomatosis, intraepidermal vesicles, RBCs in dermis and mild vasculitis like changes were more common in biopsies from herald patch as compared to secondary lesions. On comparing histopathologic features of recent lesions and older lesions, it can be concluded that some repair mechanism comes into play in older lesions which show regeneration of granular cell layer and decreased dyskeratosis.
| References|| |
|1.||Unna PG. Die histopathologic der Hautkrankahaten pp 272-276. |
|2.||Lowenbach G. Histopathologische Befunde bei herpes tonsurans maculosus it squanomosus and Pityrasis rosea. Win Med Wscha 1899; 12: 632-634. |
|3.||Solo LD, Ocanpo IV. Pityriasis rosada atipica. Int J Derm 1974; 13: 215-225. |
|4.||Bunch LW, Tilley JC. Pityriasis rosea, a histologic and serologic study, Arch Dermatol 1961; 84:79-86. |
|5.||Okamoto H, Imanura S, Aoshima T, et al. Dyskeratosis degeneration of epidermal cells in pityriasis rosea. Br J Dermatol 1982; 107:189-194. |
|6.||Pannizon R, Block PH. Histopathology of pityriasis rosea Gilbert. Dermatologica 1982; 165: 551-558. |
|7.||Amer M, Mostafa FF, Tosson Z, et al. Corneocytes in scaly parakeratotic diseases. Int J Dermatol 1996; 35: 417-421. [PUBMED] |
|8.||Dargo F, Ranieri E, Malaguti F, et al. Human herpesvirus 7 in patients with pityriasis rosea. Electron microscopy investigations and polymerase chain reaction in mononuclear cells, plasma and skin. Dermatology 1997; 195: 374-378. |
[Table - 1], [Table - 2], [Table - 3]