Granulomatous Panniculitis as a Complication of Subcutaneous Testosterone Pellet Therapy.

A 51-year-old man with a 3-year history of exogenous testosterone pellet injections to the left buttock presented for routine skin examination. While the patient reported recurrent drainage from the site of testosterone replacement therapy (TRT) injections, he continued to receive repeated implantations every 6 months. On physical examination, a 12-mm irregular, brown macule was identified within a poorly demarcated, ecchymotic, and fluctuant subcutaneous plaque on the left buttock with a sinus tract draining serosanguinous fluid. The pigmented lesion was biopsied, revealing malignant melanoma in situ; hence, a wide local excision was scheduled. During the procedure, necrotic subcutaneous fat was observed surrounding the site of biopsy, and a region measuring 18 cm2 approximately was debrided and submitted for pathologic evaluation. Histopathologic examination revealed a diffused subcutaneous granulomatous infiltrate with septal and lobular panniculitis and fat necrosis as well as peripherally palisading histiocytes and hemosiderin deposition (Figures 1A and B). Similar findings were observed in another specimen from the same segment of debrided tissue, compatible with granulomatous panniculitis. Periodic acid-Schiff (PAS), Gram's, and acid-fast bacilli (AFB) stains revealed no microorganisms. During surgical exploration, six foreign bodies were discovered and identified as undissolved testosterone pellets. The patient was referred to a wound care center, but ultimately lost to follow-up.

Cutaneous Desmoplastic Leiomyosarcoma Development at Smallpox Vaccination Site.

An 81-year-old man presented to the clinic with a 2.1 cm firm, skin-colored subcutaneous tumor on the left upper arm (Figure 1). The lesion arose at the site of a past smallpox vaccination and had been slowly enlarging for approximately 4 years. The differential diagnosis included sympastic leiomyoma, and a variety of desmoplastic spindle cell lesions such as desmoplastic melanoma, cutaneous spindle cell carcinoma, and desmoplastic leiomyosarcoma. Punch biopsy and immunohistochemical staining revealed positive spindle cells for desmin and caldesmon (Figures 2 and 3). Immunostain for p53 was also strongly and uniformly positive. Owing to poor circumscription on histopathology, symplastic leiomyosarcoma was ruled out. Demoplastic melanoma was also excluded due to positive immunoreaction to muscle markers (desmin and caldesmon) and negative S-100 staining. Additionally, cutaneous spinde cell carcinoma was also ruled out due to negative p63 and cytokeratin staining. Ultimately, clinicopathologic correlation favored a diagnosis of desmoplastic leiomyosarcoma. Staged excisions were performed to eradicate the lesion.

Multinucleate cell angiohistiocytoma.

Multinucleate cell angiohistiocytoma (MCAH) is a rare cutaneous entity described as grouped erythematous to violaceous papules. Histopathologic findings include vascular proliferations with multinucleate giant cells and dermal fibrosis. We report a case of MCAH in an 83-year-old white man affecting both the right anterior thigh and left posterior calf. Additionally, the pathogenesis of MCAH and different therapeutic modalities are reviewed.

Primary melanoma of the skin and cutaneous melanomatous metastases: comparative histologic features and immunophenotypes.

Through careful clinicopathologic correlation, we identified 37 metastatic melanomas in the skin, all of which had intraepidermal components. These were compared with 43 microscopically similar primary melanomas with a predetermined panel of immunostains in general use in surgical pathology, including bcl-2 protein, mutant p53 protein, Ki-67 (MIB-1), proliferating cell nuclear antigen (PCNA), alpha-isoform actin, and CD117 (c-kit protein). There was no significant difference in bcl-2 or alpha-isoform actin staining patterns of primary vs secondary cutaneous melanomas. The expression of Ki-67 generally was higher in metastatic melanomas than in primary lesions, and the same was true of mutant p53 protein labeling; however, some overlap was observed. CD117 staining was retained in 65% of metastatic melanomas (24/37) when they originated from ocular primary tumors; nevertheless, that marker was lost in virtually all of the other metastatic melanocytic neoplasms, whereas primary melanomas demonstrated consistent reactivity for c-kit protein. Although they are not definitive, these trends in immunoreactivity could facilitate the process of distinguishing the multiple primary melanoma syndrome from melanomatous metastases to the skin. That undertaking is best approached with circumspection, because clinicopathologic discriminators for this diagnostic separation are still imperfect.

The mouse model of amebic colitis reveals mouse strain susceptibility to infection and exacerbation of disease by CD4+ T cells.

Amebic colitis is an important worldwide parasitic disease for which there is not a well-established animal model. In this work we show that intracecal inoculation of Entamoeba histolytica trophozoites led to established infection in 60% of C3H mice, while C57BL/6 or BALB/c mice were resistant, including mice genetically deficient for IL-12, IFN-gamma, or inducible NO synthase. Infection was a chronic and nonhealing cecitis that pathologically mirrored human disease. Characterization of the inflammation by gene chip analysis revealed abundant mast cell activity. Parasite-specific Ab and cellular proliferative responses were robust and marked by IL-4 and IL-13 production. Depletion of CD4(+) cells significantly diminished both parasite burden and inflammation and correlated with decreased IL-4 and IL-13 production and loss of mast cell infiltration. This model reveals important immune factors that influence susceptibility to infection and demonstrates for the first time the pathologic contribution of the host immune response in amebiasis.