Metastatic Cutaneous Tubercular Abscesses in a Neglected 8-year-old Boy

Madam, Metastatic cutaneous tubercular abscess or tubercular gumma poses diagnostic challenges, particularly in children, given its rarity and diverse clinical manifestations. Here, we present a case of acute tubercular gumma in an unvaccinated 8-year-old boy. An 8-year-old boy presented with a sudden onset of generalized eruption of multiple abscesses and discharging sinuses for 7 days. The lesions initially appeared on his right arm and gradually spread to involve other body parts in a span of a week. The patient’s mother denied a history of fever or any other acute symptoms. There was no personal or family history of tuberculosis (TB). The child had not been immunized with bacillus Calmette–Guerin (BCG) vaccine at birth. On general physical and anthropometric examination including assessment of weight for age, height for age, and weight for height, the findings were appropriate for his age. On local examination, the abscesses and discharging sinuses were observed over the chest and bilateral upper and lower limbs. The discharge was profuse, purulent, and nonfoul smelling [Figure 1]. No lymphadenopathy was noted. Other mucocutaneous and systemic examinations were unremarkable.Figure 1: Multiple crusted ulcers and discharging sinuses present over (a) chest, abdomen, (b) back, (c) bilateral thighs and legs, (d) arms and forearms, and external aspect of the right arm with profuse purulent dischargeLaboratory investigations revealed a markedly elevated erythrocyte sedimentation rate (ESR) (100 mm/h) with neutrophilic leukocytosis. Mantoux test showed an induration of 2 mm. The viral markers were negative. Skin biopsy revealed ill-defined epithelioid cell granulomas with suppurative necrosis [Figure 2a and b]. X-ray of the right arm revealed a radio-opaque shadow, suggestive of subcutaneous abscess and radiolucent shadows (air along the sinus tract) in the right axilla [Figure 2c and d]. Ultrasonography of the right arm revealed a small heterogeneous hypoechoic collection in the intermuscular plane. The ultrasound of the abdomen revealed normal findings.Figure 2: (a) Photomicrograph (×100, H and E) displaying eroded epidermis with multiple granulomas in the upper and mid dermis. (b) Photomicrograph (×400, H and E) showing epithelioid cell granuloma with abundant neutrophils, lymphocytes, and dermal necrosis. (c and d) Anteroposterior and lateral chest radiographs exhibiting a radiolucent sinus tract (arrow) in the right axilla and a single radio-opaque shadow in the right arm’s muscular planeCartridge-based nucleic acid amplification test (CBNAAT), Ziehl–Neelsen and periodic acid-Schiff staining on pus, and tissue biopsy were negative. No organism growth was observed on a bacterial, mycobacterial, atypical mycobacterial, or fungal culture. Based on the clinical history and examination, a provisional diagnosis of tubercular gumma was considered. Subsequently, a daily regimen of antitubercular treatment (ATT) consisting of isoniazid, rifampicin, pyrazinamide, and ethambutol was started. A follow-up at 2 months [Figure 3] revealed no new lesions and complete healing of previous sinuses with superficial scarring and pigmentary changes.Figure 3: (a-d) Marked improvement in the cutaneous lesions, healing with postinflammatory hypopigmentation and atrophic scarring, 2 months after initiating antitubercular therapyMetastatic tubercular abscess is characterized by subacute hematogenous dissemination of tubercular bacilli in immunocompromised or malnourished individuals. Clinically, it presents as multiple ulcerated nodules with draining sinus tracts.[1] In this case, the child did not exhibit any signs of immunocompromised status or malnutrition, although he was not immunized with BCG. The occurrence of tubercular gumma in an immunocompetent individual is unusual.[2,3] However, since India is an endemic country for TB, the mere absence of immunocompromised status or malnourishment cannot conclusively rule out TB gumma in the present case. To our knowledge, TB gumma has not been previously reported in immunocompetent pediatric populations. Other atypical findings included nonsignificant Mantoux reading and absent lymphadenopathy. Tubercular gumma can resemble scrofuloderma;[4] however, the latter exhibits a connection with underlying structure (bone, lymph nodes, or glands). Histologically, tubercular gumma is characterized by granulomatous inflammation with caseous necrosis and the presence of acid-fast bacilli. Negative results can be supplemented by molecular tests like CBNAAT, but their sensitivity in detecting mycobacteria varies (4.5%–88%). This variation may arise from differences in gene target sequences, study areas, study designs, DNA degradation in archival materials, decreased amplification, and the presence of polymerase chain reaction-inhibiting substances.[5] Thus, a thorough clinical examination remains the gold standard for the evaluation and treatment of cutaneous TB and mycobacterial skin infections. In the present case, the diagnosis of tubercular gumma was based on a high clinical suspicion with supportive histopathological findings, elevated ESR, and complete response to ATT. This emphasizes the intricacies associated with diagnosing cutaneous TB in pediatric patients, especially in regions where the disease is prevalent, highlighting the crucial need for early identification and swift initiation of treatment. Declaration of consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.