Lobomycosis Clinical Presentation

Updated: Mar 07, 2022
  • Author: Manuel Valdebran, MD; Chief Editor: Dirk M Elston, MD  more...
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Skin lesions develop slowly. [65] For example, the incubation time in the patient who acquired the disease from an affected dolphin was 3 months, [37] and the incubation period in the American who had traveled to Venezuela was 2.5 years. [31]

When a volunteer was inoculated with the etiologic agent, the lesion was 1 X 2 mm in the first month, and then it waxed and waned. At 5 months, the lesion was a 2- to 3-mm, red papule. At 15 months, it measured 1 cm, with a small telangiectasis. At 25 months, the lesion was 15 X 10 mm, and at 4 years, it measured 33 mm in diameter, and a 4-mm satellite lesion developed. [44]

Because of this slow growth, patients do not present for many years, or they may present only after the lesions become large. The lesions often begin as small papules or pustules, and they may occur at sites of minor trauma. [44]  The lesions may be mildly pruritic, or they may burn. [62]  Single lesions occasionally regress and form scars. However, the disease never disappears, and organisms are identifiable in the scar tissue. [66]  Aside from occasional lymphadenopathy, patients lack other systemic symptoms. [63] However, a recent case report describes a squamous cell carcinoma arising in old lobomycosis lesion scars. [67]


Physical Examination

The disease predominately affects exposed areas and extremities. Examples include the ears, buttocks, lumbosacral area, scapular area, elbows, and lower limbs. [68] The scalp and mucosae are spared.

Lesions, papules, or plaques are most often described as keloidal, but the adjectives gummatous, verrucous, or ulcerative have also been applied. [18]

Lesions have well-defined lobulated margins and are not attached to deeper structures. [69]

The epidermis may be shiny, atrophic, and discolored. [18]

The disease may spread proximally from the extremities and fungal cells have been found in the lymph nodes, indicating lymphatic spread. [51, 70]  Lymph nodes that drain the affected regions may be enlarged and infected with the organism in 0-25% of patients. [18]

See the images below.

Keloidal nodule on the leg. Courtesy of Dr Roberto Keloidal nodule on the leg. Courtesy of Dr Roberto Baruzzi, Sao Paulo, Brazil.
Lobomycosis in this patient appears as a flat plaq Lobomycosis in this patient appears as a flat plaque lesion. Courtesy of Dr Roberto Baruzzi, Sao Paulo, Brazil.
Separate keloidal lesions in a localized area. Cou Separate keloidal lesions in a localized area. Courtesy of Dr Roberto Baruzzi, Sao Paulo, Brazil.


Other than geography and possible implantation of organisms through skin trauma, [71] no predisposing factors have been identified.

Important data regarding the interplay among genetic, cultural, and geographic factors have been derived from studies of the Caiabi Indians of Brazil. After they relocated to a geographic area similar to their former one, no new cases have been reported. Furthermore, their original neighbors did not have similar prevalence rates. [72]

Immunodeficiencies appear to occur in patients with lobomycosis. These immunodeficiencies include a delayed skin allograft rejection, a failure to sensitize to dinitrochlorobenzene, and an anergy to Candida species. [73]  Whether the immunodeficiencies are primary and predispose patients to infection or secondary and the result of infection is not known. Based on the large number of fungal cells in the infected tissue and the disorganized cell arrangement in the granuloma, it has been hypothesized that patients with lobomycosis have immunoregulatory disturbances, which are likely to be specific and perhaps responsible for the lack of containment of the pathogen. [74]  One patient infected with HIV has been reported to have lobomycosis. [75]