By ProPath Staff
Kaposi’s sarcoma is a proliferation of atypical spindle cells that exhibit endothelial differentiation. Although this condition may in rare instances become life threatening due to visceral involvement (most commonly lungs), its medical significance is more commonly related to its close associated with acquired immunodeficiency syndrome (AIDS).
Whether arising in young persons with immunodeficiency or in older person’s of Mediterranean descent, Kaposi’s sarcoma quite commonly affects the skin of the lower extremities. It’s high prevalence amongst soft tissue tumors of the lower extremity has been recorded in the literature. In a review of 401 soft tissue tumors published in 2001, a shocking 16% of all lesions were Kaposi’s sarcoma. The relative frequency with which this tumor is diagnosed in the lower extremity has been noted by others. The “classic” clinical image of Kaposi’s sarcoma is one of a welldeveloped geographic red patch or plaque; however, in actuality, there is a wide spectrum of clinical presentations. Not uncommonly
lesions may present as a solitary papule or nodule. It is not uncommonly mistaken for pyogenic granuloma, hemangioma, or a simple “blood blister” (Fig. 1). Because it may masquerade as various clinically insignificant entities, its diagnosis may be delayed for extended periods of time if a biopsy is not performed.
From the histopathologic perspective, Kaposi’s sarcoma has a characteristic, but not always specific, histologic appearance. It is comprised plump spindle cells forming slit-like spaces. In some instances the neoplasm is lobulated in a pattern reminiscent of pyogenic granuloma. There are commonly abundant extravasated erythrocytes. When papules or nodules form on the sole, ulceration may occur, further confusing the histologic (and clinical) appearance.
In recent years, Human Herpes Virus, Type 8 (HHV8) has been closely linked to Kaposi’s sarcoma of all types. Using immunohistochemical techniques, HHV8 latent nuclear antigen may be identified in nuclei of lesional cells. This technique, offered at ProPath, helps to distinguish genuine Kaposi’s sarcoma from similar appearing vascular proliferations (Fig. 3). Pearl: Deep shave biopsy is ideal (CPT 11307).
1. Bakotic BW, Borkowshi P. Primary soft tissue neoplasms of the foot: J Foot Ankle Surg 2001; 40:28-35.
2. Berlin S, Statistical analysis of 307,601 tumors and other lesions of the foot. J Am Podiatr Med Assoc 1995; 85:699-703.
3. Herman PS, Shogreen MR, White WL. The evaluation of HHV8 in cutaneous lesions.. Am J Dermatopathol 1998; 20:7- 11.
Podiatric Dermatology as a Clue to Systemic Disease:
Dermatological changes in the lower extremity may connote the presence of a related systemic disease. This point, although widely taught in Podiatric curricula, may be overlooked by clinicians who become complacent with regard to their important role in dermatology. Only by maintaining a keen eye and performing biopsies when indicated, can such associations be identified. Case in point; Erythema Nodosum (Fig. 4).
Erythema nodosum (EN) is a pattern of inflammation which is seen in association with various disease processes. It arises as deep-seated, painful nodules, most often on the lower legs and less commonly on plantar surfaces. EN may be associated with sarcoidosis, inflammatory bowel disease, leukemia/lymphoma, various bacterial and viral infections, and my arise in the context of a drug reaction.
Clinically, the differential diagnosis includes numerous other forms of panniculitis, among them, necrobiosis lipoidica, traumatic panniculitis, and nodular vasculitis. In addition, when solitary, EN may mimic a florid arthropod assault or a subcutaneous neoplastic process.
Histopathologically, EN may be identified by its characteristic granulomatous inflammation involving subcutaneous fibrous septae (Fig. 5). In acute lesions, giant cell histiocytes are easily identified (Fig. 6). Such cases provide an excellent illustration of why deep punch biopsies are ideal for inflammatory conditions. Because the diagnostic tissue is located in the deep dermis and subcutis, superficial biopsies will be entirely nonspecific. Pearl: 3, 3.5, and 4 mm punches are ideal (CPT:11000)
1. Ohtake N, et al. Unilateral plantar erythema nodosum. J Am Acad Dermatol 1994; 30: 654-655.
2. Cribier B et al. Erythema nodosum and associated diseases. Int J Dermatol 1998; 37:667-672.
Cardinal Sin in Podiatric Dermatology
In every facet of each profession, in every position of every sport, and in nearly every past-time, there is a “cardinal sin”. The one mistake which simply “can’t happen”. The one error that will not, and should not, be forgiven. The practice of podiatric dermatology has its own cardinal sin.
In the past several months I have witnessed two independent cases where a podiatric clinician debrided or excised a lesion, and believing it was benign, passed on pathologic exam, rather opting for the waste basket. In both cases, rather than a verruca or foreign body, respectively the lesion was an amelanotic or only partially pigmented melanoma. In both cases, a patient was subsequently told that their condition was terminal because of a delay in diagnosis.
Histopathology provides clinicians with both documentation that a procedure was done and documentation of benignancy. The bottom line? “If it’s not conventional, send for histopathologic examination”.
Special thanks to Robert Taylor, D.P.M. and Donald Wheat, D.P.M. for their clinical insights and contributions.
Date of last revision: Spring 2003.