General Remarks on the Disease.
From the above description and the cases related in support of it, what inference may be drawn as to the nature of the disease and its relation to other skin affections? Frankly, at present I am quite unable to even conjecture its pathology, or to suggest, with one exception, any relation to other dermatoses. In my first cases I supposed that it was an early stage of Mycosis fungoides, though the absence or trifling character of the subjective symptoms did not lend this any support. I clung to this theory, however, faute de mieux, for a long time, but it received its coup de grace when I met with a case of over thirty years’ duration without any such malign development.
At the Dermatological Society of London, where Mr. George Pernet and myself have shown three cases, among other suggestions, that of a possible seborrhoïde or Urticaria pigmentosa have been made. Against the former, the absence of scaliness in a large proportion of the patches, that the patches are in the skin, not raised above, and that itching is an exceptional feature, together with the unchanging character of the lesions, effectually bar the diagnosis of a seborrhoïde. Neither can I find anything beyond the yellowish tint frequently, but not always, present to support the idea of Urticaria pigmentosa. The absence of itching in nearly all the cases of Urticaria factitia, while the patches are level with the normal skin, and their unchanging character, are all strongly against such a diagnosis, to say nothing of the extreme rarity of adult Urticaria pigmentosa and the improbability of one man meeting with nine cases of it. The histology also negatives this.
I can therefore, at present, only regard it as a dermatosis sui-generis, of which the pathology must be left an open question, as Mr. George Pernet’s report on the histology of the portion of skin removed from Case 8 does not throw much light upon the pathology. There remains only the affection described by Brocq, to which, certainly, there are closer resemblances than to any other affection.
Brocq[[1]] divides the group which he calls parapsoriasis into three groups:
First variety (very closely related to psoriasis), Parapsoriasis guttata. Jadassohn’s case is probably to be referred to it.
Second variety (intermediate between Lichen and psoriasis), Parapsoriasis lichenoides, including Parakeratosis variegata of Unna, and Lichen variegatus (Crocker).
Third variety (closely allied to Seborrhœa psoriasiformis), Parapsoriasis in patches, corresponding to Erythrodermie pityriasique en plaques disseminées of Brocq, and of which cases have also been reported by J. C. White and C. J. White.
It is only with the third variety that comparison need be made, the deep colour and very small pattern, like a mosaic of the first two, sharply contrasting with the broad effects as of colour dashed on, in Xantho-erythrodermia perstans.
For the whole group Brocq gives the following characteristics:
(1) An almost complete absence of pruritus.
(2) A very slow evolution.
(3) A distribution in circumscribed, sharply defined patches, whose dimensions are from 2 cm. to 6 cm. in diameter, and which are scattered here and there over the integument.
(4) An almost complete absence of infiltration of the derma.
(5) A pale redness (pinkish coloured).
(6) A fine pityriasic desquamation.
(7) An extraordinary resistance to the local applications usually employed in the treatment of psoriasiform or pityriasic seborrhœa, in fact, only yielding slowly and imperfectly to the most energetic application of pyrogallic acid.
The special features of the third variety he describes as:
(1) Being in patches, circumscribed, sharply defined from 2 cm. to 6 cm. in diameter.
(2) They are scattered irregularly over the skin without any apparent system.
(3) The colour varies from a pale red to a brownish or livid red, according to the part affected.
(4) There is always present a fine pityriasic desquamation more or less marked in different cases.
(5) There are at times in some of these cases, aggregations of small flattened papules which may be considered as links connecting it with the second variety.
(6) There is no infiltration of the integument appreciable to the eye or touch.
(7) The face is rarely affected, and there is the same extremely slow evolution, great resistance to local treatment, and few or no subjective symptoms.
Referring to the whole group, he says: “We know nothing very definite about the etiology or pathology of these affections. They may appear at any age, but seem more frequent in youths or adults. He has observed cases in men and women and in all classes of society. They seem to be slightly more frequent in women than in men.”
It must be confessed that there are many points of resemblance of this third variety to Xantho-erythrodermia perstans, and, as regards the lady, Case 10, it is probably what Brocq has described as “Erythrodermie pityriasique en plaques disseminées,” although I should say there was distinct infiltration in a large proportion of the lesions, and many of the patches far exceeded the limits in size that Brocq lays down.
With regard to the other nine cases, the differences are somewhat more marked, and they should, at least for the present, be either kept apart or treated as a distinct variety.
The differences are:
(1) The patches are frequently much larger, 3 and 4 inches or more in their long diameter, and the margin is not very sharply defined.
(2) A distinct arrangement in lines in direction varying with the topography is observable in most cases.
(3) The colour is either pale red or distinctly yellowish.
(4) Instead of a fine pityriasic desquamation being always present, this is only distinct on the legs, sometimes just recognisable on the thighs and arms, while on the trunk it is absent, the surface being usually quite smooth.
(5) The presence of papules I have not observed, except at the commencement of Case 4.
(6) There is distinct infiltration in a large proportion of the patches, perceptible to the touch, though not to the eye.
The resemblances are: the absence of conspicuous pruritus, and there is often none; the occurrence in patches; the slow evolution; a pale redness; in many cases an extraordinary resistance to treatment. These are not enough to establish identity, but I confess that in my opinion they show greater resemblance to the affection I am describing than they do to psoriasis, and certainly my nine male cases would never suggest to any one a resemblance to psoriasis, and I should strongly demur to class them under parapsoriasis as a covering term.