Cutaneous digital tuberculosis in immunocompetent host.

A 36-year-old man without any medical history presented with a 2 cm isolated well limited non-purulent papillomatous, erythematous lesion on the 4th finger of the right hand evolving for 9 months (Fig. 1). He reported no trauma. The general physical examination and the hand X-ray were completely normal. The initial biopsy revealed epithelioid and giant cell granuloma without necrosis (Fig. 2) and with a negative AFB stain leading to a chronic acneiform dermatitis diagnosis. Treatment with topical corticosteroids were not effective. Second biopsy wasn’t more contributive including specific bacterial and fungal culture. A third biopsy was performed looking for mycobacteria which was negative in direct examination and specific PCR but culture returned positive for multi-sensitive Mycobacterium tuberculosis after one month. The patient were totally asymptomatic for general tuberculosis symptoms. Nevertheless a chest scan was performed due to the diagnosis of cutaneous digital tuberculosis bringing to light a cavernous extensive pulmonary tuberculosis (Fig. 3). Sputa were positive on direct examination and culture for Mycobacterium tuberculosis. HIV serology and pursuit for primary immunodeficiency were negative. A classic quadritherapy was initiated with a rapid regression of the cutaneous lesion (Fig. 4). The case investigation permitted to identified 1 secondary pulmonary tuberculosis, 3 cases of latent tuberculosis, and 2 infants in the patient's entourage requiring treatment.

Fig. 1

Cutaneous lesion at the diagnosis of tuberculosis.

Fig. 2

Histopathology of the skin lesion with epithelioid and giant cell granuloma without necrosis.

Fig. 3

Chest scan revealing extensive tuberculosis with multiple cavernous.

Fig. 4

Cutaneous lesion after 3 month of treatment.

Tuberculosis remains a common disease affecting 10 million people a year and responsible for 1.6 million deaths in 2017 [1]. The cutaneous localization represent less than 1%, including in highly endemic regions [2]. They manifest themselves heterogeneously depending on the patient immunity, as in Hansen disease with pauci and multi bacillary forms. The diagnosis must be made in the presence of a chronic papillomatous skin lesion associated with granulomatous histology. We report here a rare form of cutaneous localization of tuberculosis [3]. This clinical case reminds us that the presentation of tuberculosis can be atypical and that its early diagnosis remains a major issue.

CRediT authorship contribution statement

A. Redor: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Resources, Software, Supervision, Validation, Visualization, Writing - original draft, Writing - review & editing. A. Baeke: Writing - review & editing.