Keloidal blastomycosis or Lobo's disease

Lobomycosis is a rare chronic cutaneous infection caused by Lacazia loboi previously called Loboa loboi. The disease manifests as keloids, verrucoid to nodular lesions, crusty plaques, and tumors. The fungus grows as globose cells that are connected to each other by a narrow neck. The cells may form branching chains. Developing lesions are well defined, smooth, painless and easily moved around since they lie free over the deeper tissues. Older lesions typically become verrucoid and ulcerative with satellite lesions resulting from autoinoculation [347, 1114, 1944].

Cutaneous and subcutaneous.

Lesions are managed by surgical excision. Since frequent relapse occurs, the excision must be wide. Surgery may result in new lesions [1943].

Nodules consist of subepidermal histiocytic granulomas that lie between the overlying skin and subcutaneous tissue. Fibrous tissue is dispersed between large numbers of giant cells and histiocytes. The giant cells are 40-80 µm in diameter. In older lesions, pyogenic infiltrates, parakeratosis, and acanthosis are present. Pseudoepitheliomatous hyperplasia and intraepidermal abscesses are absent. The fungus occurs as chains of globose cells 7-14 µm (average 9-10 µm) in diameter. Each cell is connected to the adjacent cell by a narrow neck. Some yeast cells occur within giant cells and macrophages, but the majority surround these cells.

Direct examination

Direct examination of clinical material, cutaneous and subcutaneous tissue, is mounted in 10% KOH and examined for the presence of chains of globose cells.

Isolation

Isolation of the fungus has never been achieved, except in mice foot pads.

Unknown, but the infection is also found in dolphins

PubMed

Lobomycosis of leg

H & E stained tissue infected with Lacazia loboi

Arm with Lobomycosis

GMS stain of tissue infected with Lacazia loboi

References

347. Burns, R. A., J. S. Roy, C. Woods, A. A. Padhye, and D. W. Warnock. 2000. Report of the first human case of lobomycosis in the United States. J Clin Microbiol. 38:1283-5.

1114. Jaramillo, D., A. Cortes, A. Restrepo, M. Builes, and M. Robledo. 1976. Lobomycosis. Report of the eighth Colombian case and review of the literature. J Cutan Pathol. 3:180-9.

1943. Rodriguez-Toro, G. 1993. Lobomycosis. Int. J. Dermatol. 32:324-32.

1944. Rodriguez-Toro, G., and N. Tellez. 1992. Lobomycosis in Colombian Amer Indian patients. Mycopathologia. 120:5-9.