Cutaneous Mycobacterial Spindle Cell Pseudotumor

It seems cutaneous infections have taken over my posts. I guess I get more excited about cases when the special stains actually identify organisms.

This is a very interesting lesion as it presented as a cutaneous nodule and the clinical suspicion was for metastatic disease vs. infection in an immunocompromised patient with a history of non-cutaneous malignancy. There is a diffuse dermal histiocytic infiltrate with a somewhat spindle cell morphology associated with scattered lymphocytes and neutrophil. The AFB Ziehl-Nielson stain show numerous acid fast bacilli. They are also identifiable in the PAS-stained sections. Identical PAS-staining was noted in a recent Am J Dermatopathol article. The pattern seems to fit well for the so-called mycobacterial spindle cell pseudotumor. The organisms that cause this include Mycobacterium avium-intracellulare, M. kansasii, M. chelonae, M. gordonae, M. scrofulaceum, and of course M. tuberculosis should be ruled out.  I’ll leave it to the cultures to decide.

Cutaneous mycobacterial spindle cell pseudotumor: a potential mimic of soft tissue neoplasms. Am J Dermatopathol. 2011 Aug;33(6):e66-9. Yeh I, Evan G, Jokinen CH.

Cutaneous mycobacterial spindle cell pseudotumour.  BMJ Case Reports 2009;  Geok Chin Tan, Yen Piow Yap, Mohd Sidik Shiran, Abdul Rahman Sabariah, Rajadurai Pathmanathan

Mycobacterial spindle cell pseudotumor of the skin. J Cutan Pathol. 2007 Apr;34(4):346-51. Shiomi T, Yamamoto T, Manabe T.

Spindle cell pseudotumor due to Mycobacterium avium-intracellulare in patients with acquired immunodeficiency syndrome (AIDS). Positive staining of mycobacteria for cytoskeleton filaments. Am J Surg Pathol. 1991 Dec;15(12):1181-7. Umlas J, Federman M, Crawford C, O’Hara CJ, Fitzgibbon JS, Modeste A.


3 responses to “Cutaneous Mycobacterial Spindle Cell Pseudotumor

  1. Very interesting. I tried looking this entity up in Weedon and the new McKee but to no avail! The lesions are certainly full of organisms, presumably because of the immunosuppression from whatever. The reference cases with prednisolone and Etanercept were also good. Thanks for posting this rare entity.

  2. They seem to be more commonly reported in other sites: lymph nodes, spleen, brain, lung, nasal septum. My patient had completed chemotherapy recently, causing her immunosuppression. I only found only a few recent references to cutaneous lesions, maybe they’ll make the textbooks in the next editions. Here’s another below from Taiwan I forgot to include.

    Mycobacterial spindle cell pseudotumor of skin. Liou JH, Huang PY, Hung CC, Hsiao CH. J Formos Med Assoc. 2003 May;102(5):342-5.

  3. Pingback: Dermatopathology mycobacteria | Supermom1

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