Although HTLV-1 infection in most cases does not generate disease, it has been described that many of these patients are not entirely asymptomatic and are compromised undetected, the skin is one of the most affected organs, as evidenced by the series of cases in the blood donors [6, 12]. This fact becomes more important since our territory is recognized as an endemic area, with epidemiological data corresponding to a prevalence between 0.17–0.3%, the most affected regions are the Pacific, Caribbean and Andean region [13, 14].
Among the characteristic cutaneous manifestations directly related to infection by HTLV-1 are infectious dermatitis, crusted scabies, and skin injuries by ATLL and MPET [12, 15, 16]. According to a series of cases with more patients, in a population of Brazil, they evidenced a prevalence of skin alteration in asymptomatic seropositive patients of 76% and in those with MPET it was 88%. Among the findings, inflammatory pathologies predominated, acquired xerosis/ichthyosis and seborrheic dermatitis were the most frequent skin disorders in the adult population, with a prevalence of 60.2/42.5% (xerosis / ichthyosis) and 47.9/15% (seborrheic dermatitis) for the asymptomatic and MPET groups respectively; likewise, infectious diseases obtained a prevalence of 30%, with dermatophytosis and scabies being the most prevalent [17]. On the other hand, infectious dermatitis prevails in the child population, who are characterized by presenting generalized eczema and Staphylococcus and Streptococcus infections who require chronic antibiotic treatment because of high recurrence rate [4, 5, 18]. In 1993, Nagatani, et al. published a case report showing a possible association between PPK and HTLV-1, but a definitive diagnosis was not confirmed by biopsy [19].
Our case is relevant because it presents a cutaneous manifestation, confirmed by biopsy, which has not been described in association with HTLV-1 infection, it presents generalized cutaneous xerosis associated with PPK transgrediens, which is a condition consisting of the abnormal thickening of the epidermis of palms and plants, and additionally has the ability to affect areas beyond the palmoplantar skin, these qualities differentiate it from acquired ichthyosis, since it does not meet the clinical characteristics of the adherent visible scales, nor the alteration in the granular layer, which are documented structural characteristics in the biopsy; therefore, this pathology is ruled out.
PPK is considered an independent clinical entity that is part of the palmoplantar keratoderma group and the approach of the etiology requires the assessment of multiple systemic and non-systemic conditions that may be associated with its presentation, including infectious, malignancy, endocrine and autoimmune diseases, among others. PPK has been associated with perimenopause, the use of drugs, or infectious processes such as dermatophytosis, human papilloma virus, syphilis, leprosy, miliary tuberculosis, and scabies (ruled out pathologies in the case report) but never with HTLV [20]. Particularly, PPK secondary to human papilloma virus is especially presented in immunocompromised patients and the usual presentation is confluent verrucous masses on the palms and soles. Our case is about a patient without laboratory alterations suggesting compromise in the immune system, similarly, skin demonstrations were not the usual reported for this infection. Our experience suggests that PPK is a newly recognised cutaneous manifestation associated with HTLV-1 infection.
Furthermore, the association between HTLV-1 infection and Strongyloides stercolaris is known. The available evidence suggest HTLV-1 infection is more frequently associated (up to 2.4 times more) with Strongyloides stercolaris infection [21, 22]. Similarly, it has been suggested that Strongyloidiasis increases the risk of diseases associated with HTLV-1, modifying its viral load [23], a view that this coinfection is considered a possible risk factor for the development of lymphoproliferative syndromes associated with this virus, or even serve as a marker of severity of HTLV-1 infection [22]. Strongyloides hyperinfection syndrome, is a severe form of strongyloidiasis, has been described in patients with drug immunosuppression or secondary to malignancy, but also in cases of HTLV-1 infection [24]. Although strongyloidiasis has been associated with malabsorption syndromes, there is no clear association in literature suggesting a relationship between PPK and malabsorption syndromes of another etiology. This case is about a patient who had no clinical or paraclinical demonstration suggesting any particular systemic condition.
According to that, the evaluation of this coinfection and this cutaneous manifestation not previously described in relation to HTLV-1 infection, is important in order to carry out an adequate evaluation and follow-up, monitoring the possible progression of the disease and the development of complications to short and long term in an endemic region.