The clinical manifestations, laboratory findings and causative agents of granulomatous skin reaction

Abstract

Background: The prevalence of nontuberculous mycobacterial (NTM) infection is increasing in Thailand and cutaneous presentations of NTM infection are nonspecific and variable. The diagnosis of cutaneous NTM infection should be combined with clinical manifestations, histopathological features, tissue special stains, tissue polymerase chain reaction (PCR) and tissue culture. Thus, the diagnosis of cutaneous NTM infection is challenging; therefore, sometimes, the diagnosis and treatments can be delayed.

Objective: This study would like to improve the diagnosis when there was no evidence of organism from tissue biopsy, this study would like to investigate the correlations of history, clinical manifestations and histopathological features in the cases of tissue biopsy were granulomatous reaction and the final diagnosis as cutaneous mycobacterial infection. The secondary outcome is to investigate the correlation of history, clinical manifestation and histopathology between NTM granuloma and the other causes of infectious granuloma.  

Materials and Methods: A retrospective study of the patients with histopathological features as granulomatous reaction and suspected of cutaneous mycobacterium infection from history and clinical manifestations were obtained from the Division of Dermatology, Phramongkutklao Hospital between January 2014 and December 2016.

Result: All the 30 cases with skin biopsy compatible with granulomatous reaction were included in this study. Of the 30 cases, eight cases (26.67%) had diagnosis as NTM infection, seven cases (23.33%) had diagnosis as suspected NTM infection and 15 cases (50%) had other diagnoses. The male to female ratio was 2:3. The mean age at diagnosis was 54.4 years (range 16-94).

The history of suspected cutaneous chronic infection was significant higher in the NTM/suspected NTM infections group compared to the group with other diagnoses.  The location of the lesions in NTM/suspected NTM infection was more common on extremities. All the patients presented with red-colored nodule, papule or plaque which has no statistic significant between each group.

Most of granulomatous patterns in our study are suppurative and mixed cell granuloma. There was no correlation between histopathological findings and the demonstration of organism in tissue specimens. The tissue AFB stain in NTM-infection group is positive in 37.5% (3/8 cases) which 2 of the 3 AFB-positive cases had immunocompromised status. Tissue culture was positive in 62.5% of the NTM-infection group which M. abscessus was the most common causative organism.  The mean duration of treatments in NTM/suspected NTM infections was 6 months. 

Conclusion:Although the tissue special stains, tissue PCR or tissue culture are the most effective diagnostic tools, the rate of positivity is low in our study. The diagnosis should be suspected in the patients with suspicious history such as history of trauma, aquatic-relate injury. The prompt treatment with broad-spectrum antibiotics should be started in suspicious patients.