Unknown: Unusual Exophytic Nodule on the Plantar Foot
Cindy Chambers MPH, Victoria Sharon MD, Nasim Fazel MD DDS MAS
Dermatology Online Journal 16 (4): 11

Department of Dermatology, UC Davis, Sacramento, California

Abstract

Kaposi sarcoma (KS) may be categorized into four primary clinical variants: classic, iatrogenic, endemic or African, and epidemic or acquired immunodeficiency syndrome (AIDS)-related KS. Acquired immunodeficiency syndrome-associated Kaposi sarcoma typically presents on the face and trunk as pink to red macules and papules and can be rapidly progressive leading to disseminated visceral involvement and death. Rarely has AIDS-associated KS been described as presenting on the feet. We report a case of AIDS-associated nodular KS manifesting as an exophytic nodule on the plantar foot.



Diagnosis: Kaposi Sarcoma


Figure 1 Figure 2

Figure 3 Figure 4

A 44-year-old man presented with a six-month history of a painful progressively enlarging nodule on the plantar surface of the left foot. He reported occasional bleeding and oozing of clear to yellow fluid. On a review of systems, he also noted fatigue, dizziness, and dark stool. Past medical history was significant for AIDS diagnosed three years earlier, with noncompliance regarding previously prescribed highly active antiretroviral therapy (HAART).

Physical examination revealed a discrete exophytic friable pink nodule coated with yellow crust on the central plantar surface of the left foot (Figures 1 and 2). No regional lymphadenopathy or edema was noted. Based on the patient’s medical history and clinical presentation, our differential diagnosis included a deep fungal, bacterial, or atypical mycobacterial infection as well as nodular melanoma, lymphoma, or other neoplasm, including Kaposi sarcoma (KS). A shave biopsy from the left plantar foot was obtained for routine hematoxylin and eosin stain. Basic laboratory evaluation was obtained, significant for a CD4 count of 116 cells/mm³ (reference range 500-1500 cells/mm³), viral load of 944,000 copies/mL (reference range undetectable), and hemoglobin of 7.7 gm/dL (reference range 13.5-17.5 gm/dL). White blood cell count was normal. In the context of symptomatic anemia and reported melena, the patient was referred for further work-up secondary to concern for a gastrointestinal (GI) hemorrhage.

Histopathologic examination of the nodule from the plantar foot revealed epithelial hyperplasia with overlying hyperkeratotic crust (Figures 3 and 4). There was a diffuse dermal infiltrate characterized by a biphasic growth pattern consisting of abundant slit-like vascular spaces interspersed among fascicles of plump spindle cells. A polymorphous cellular infiltrate composed primarily of lymphocytes, plasma cells, histiocytes, and neutrophils was noted. The combined clinical, histopathologic, and laboratory findings were diagnostic of nodular Kaposi sarcoma (KS). A subsequent biopsy of intestinal epithelium via esophagogastroduodenoscopy (EGD) was consistent with visceral KS.

Because of the extensive visceral KS, Doxil (liposomal doxorubicin) was initiated with the subsequent addition of HAART. A repeat EGD after the third cycle of Doxil revealed residual KS in the stomach and duodenum, unchanged from prior. The patient, however, has not experienced ongoing GI bleeding and his hemoglobin has remained stable at 13 gm/dL. He is currently beginning his sixth cycle of Doxil with a repeat EGD planned following completion. The plantar foot healed well after shave biopsy with minimal residual post-inflammatory pigmentary alteration. There has been no cutaneous recurrence during six months of follow-up.


Discussion

Kaposi sarcoma represents a spindle-cell proliferation of purported lymphatic endothelial cell origin, most commonly occurring in four main populations [1]. Among these are classic, AIDS-associated, endemic African, and iatrogenic KS [2].

Classic KS is slowly progressive and commonly found on the lower extremities of elderly men of Eastern European, Jewish, or Mediterranean heritage [3, 4]. It is relatively benign, as the majority of patients do not ultimately succumb to the disease. In contrast, AIDS-associated KS may begin on the face, trunk, lower extremities, or oral cavity and is often characterized by multifocal widespread lesions at the onset of illness [5, 6]. Lesions typically present as discrete and violaceous macules or papules of the skin or oral mucosa that have the potential to evolve into bulky nodules and plaques [5]. Whereas classic KS is generally indolent, AIDS-associated KS can be rapidly progressive and is frequently associated with systemic involvement of the lymph nodes, GI tract, and lungs [4, 5]. Advanced AIDS-associated KS may be associated with non-pitting edema of the bilateral lower extremities, which generally represents an overall poor prognosis. Endemic KS affects a younger population and frequently follows an indolent course, but is also occasionally characterized by aggressive and widespread disease. Iatrogenic KS often results from severe immunosuppression secondary to organ transplantation and usually regresses with discontinuation of immunosuppressive therapy [3, 7].

The Schwartz et al. staging system classifies KS into four categories ranging from localized (Stage I) to disseminated disease with visceral organ involvement, most commonly of the GI tract, lymph nodes, and lungs (Stage IV) [7]. Whereas in classic KS, gut lesions are frequent and asymptomatic, in AIDS-associated KS, GI lesions may lead to massive hemorrhage [7]. Our patient had visceral AIDS-associated KS (Stage IV) complicated by hemorrhage.

The clinical differential diagnosis of KS is broad and includes pyogenic granuloma, angioma, melanoma, bacillary angiomatosis, blue rubber bleb nevus syndrome, angiosarcoma, acroangiodermatitis, and cutaneous metastases [7]. Histopathology of KS commonly reveals a dermis with increased spindle cells and vascular slit-like spaces. Extravasated erythrocytes are common and a polymorphous inflammatory infiltrate with numerous plasma cells is seen [2]. Staining for human herpes-virus 8 (HHV-8) can serve as a useful diagnostic tool; HHV-8 is consistently associated with KS and can be detected by polymerase chain reaction in nearly 100 percent of cases [4].

The optimal treatment of KS varies by individual circumstance. Options for local therapy include topical retinoids, liquid nitrogen, surgical excision, laser or photodynamic therapy, radiation, and intralesional chemotherapy. Available systemic therapy includes interferon, chemotherapy, and HAART [7, 8].

Although the incidence of KS as an AIDS-defining illness has decreased dramatically since the induction of HAART, it remains the most frequent AIDS-associated neoplasm and is a common source of morbidity and mortality [5, 7]. AIDS-associated KS is rarely reported to present on a distal extremity and there are limited published cases in the literature describing this phenomenon on the feet [9]. The atypical location, lack of multifocal involvement, and absence of a characteristic violaceous color of the plantar lesion made KS less likely among a variety of alternative etiologies.Had our patient’s lesion been evaluated sooner, extensive GI involvement may have been detected earlier, perhaps preventing subsequent extensive hemorrhage.

The current case supports a highly variable clinical spectrum of KS and suggests a consideration of the diagnosis in all AIDS patients with unusual exophytic growths.

References

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