Prototheca, a genus of achlorophyllic algae, is a rare cause of opportunistic infection in humans. About 80 human cases, mostly cutaneous infection caused by P. wickerhamii, have been reported world-wide. We describe the clinicopathological findings and treatments of five cases diagnosed in our department during the period 1991-97. The patients, including four elderly farmers, presented with pyoderma-like lesions or infiltrating papules and plaques on the extensor side of the extremities or face. All patients were immunocompromised, mostly due to systemic or topical steroids. The diagnosis was made in each case by finding typical endospores with morula-like structures in skin biopsy specimens. P. wickerhamii was isolated in four cases in which pretreatment culture of skin tissue was done. Except for one patient who died of asthma, the infection was cured after 2-7 weeks of amphotericin B, ketoconazole, itraconazole or fluconazole. Our cases illustrate that cutaneous protothecosis commonly manifested non-tender, pyoderma-like or infiltrating lesions and should be considered in the differential diagnosis of deep fungal or mycobacterial infection. This rare infection seemed more frequent in our region, possibly due in part to common steroid abuse among old people in Taiwan and there was a large population of elderly farmers in our area.

A 50-year-old man presented with severe mucosal erosions of the lips, oral cavity and perianal area, a lichen planus-like eruption on the trunk and extremities and scaly plaques of the palms and soles. The clinical impression was of Stevens--Johnson syndrome, or paraneoplastic pemphigus (PNP). Histopathology revealed vacuolar interface and lichenoid dermatitis with dyskeratosis and suprabasal acantholytic vesiculation. Direct immunofluorescence showed deposition of IgG in the intercellular space and linear deposition of C3 along the basal membrane zone. Indirect immunofluorescence revealed circulating IgG with intercellular staining of the epithelium of rat urinary bladder. Western blotting demonstrated bands of 250- and 230-kDa antigens. The clinical, histological and immunological features were consistent with the lichen planus pemphigoides variant of PNP. A retroperitoneal hyaline-vascular Castleman's disease was detected and excised. The skin lesions worsened initially after tumour resection but improved gradually, leaving extensive melanosis after cyclosporin and mycophenolate mofetil treatment.

Alopecia syphilitica (AS) may be "moth-eaten" or diffuse, clinically, and be confused with alopecia areata (AA) or other alopecias. The English language literature contains scant information regarding the histopathology of AS, and the resemblance between AS and AA has not been given adequate recognition. We report the histopathological findings of AS from nine patients with secondary syphilis and acute hair loss. The alopecia was moth-eaten in four patients and diffuse, but slightly moth-eaten, in five. Microscopically, the dermoepidermal interface was not involved. The numbers of hair follicles were diminished, with increased numbers of catagens and telogens. Lymphocytic infiltration was present around the hair bulbs and fibrous tracts in eight cases. Plasma cells were present in four biopsies. Other less common findings included lymphocytes in the isthmus, parabulbal lymphoid aggregates, and granulomatous infiltrate in the upper dermis. The findings, save for the follicular changes, resembled those of macular/maculopapular syphilides outside the scalp. With the follicular changes, the overall patterns resembled AA closely. The modified Steiner stain did not reveal spirochetes in any of our cases and failed to differentiate between AS and AA. Comparing the AS cases to 13 cases of AA, we found only a few differentiating features. The presence of peribulbal eosinophils strongly suggests AA. Without peribulbal eosinophils, the presence of plasma cells, abundant lymphocytes in the isthmus, or parabulbal lymphoid aggregates suggests AS.