Rosen's Breast Pathology, 4e

925

Unusual Clinical Presentation of Carcinoma

A

B

FIG. 33.35.  Primary inflammatory carcinoma, cutaneous pathology. A: A cluster of carcinoma cells is present in a lymphatic space in the dermis. B: A solitary cluster of cells “suspicious for carcinoma” is seen in this punch biopsy of skin performed to rule out inflammatory carcinoma. The differential diagnosis includes carcinoma, histiocytes, and endothelial hyperplasia with “telescoping.” The endo- thelial lining cells display immunoreactivity for D2-40 and factor VIII, and the “suspicious” cells are ­cytokeratin (ck) positive. These findings are diagnostic of dermal lymphatic involvement by carcinoma.

A lymphoplasmacytic reaction may be encountered in the carcinoma or in the surrounding breast, but it does not differ in intensity, pattern, or frequency from the findings in patients with noninflammatory carcinoma. 234,268,269 The intensity of the inflammatory reaction in the breast and skin is usually similar, but these reactive components have not been found to correlate with the severity and distribu­ tion of the clinical cutaneous manifestations of the disease. That is, ­patients with the most marked lymphoplasmacytic reaction do not necessarily have the most intense cutaneous erythema or the most severe edema. There is also no direct relationship between the number of lymphatic tumor em­ boli or the extent of vascular distension and the clinical find­ ings. Neutrophils, eosinophils, or numerous mast cells are not a common feature of IBC. Because the cutaneous manifestations of IBC are so clini­ cally striking, there has been a great deal of interest in the microscopic pathology of the skin. An incisional biopsy of the skin is often performed for diagnostic purposes, but the diagnosis of carcinoma can be made easily by needle biopsy of the breast if there is an underlying palpable mass. It is not necessary to obtain a skin biopsy to establish the diagnosis of IBC when a patient presents with characteristic clinical findings and a biopsy-proven breast carcinoma. The skin often displays a variety of histologic alterations associated with IBC (Fig. 33.35). The collagenous reticular dermal layer is broader than normal because of increased amounts of collagen and edema. Dilation of lymphatics tends to be prominent in the papillary and reticular dermis, and intralymphatic tumor emboli can be found at either level of the dermis. When present, a lymphoplasmacytic re­ action is localized around dilated lymphatic channels. The microscopic pathology of the skin varies greatly among patients with IBC. Histologic features of the skin may

not correlate with the clinical findings. Samples of skin from within and outside the zone of erythema and edema may appear histologically similar, with lymphatic tumor emboli detectable in areas that appear clinically uninvolved. When carcinoma is found in the skin of a patient with primary IBC, it is usually limited to lymphatic emboli. Extralymphatic dermal tumor infiltrates are uncommon. FNA in suspected cases of IBC presenting without a palpable mass may be suc­ cessful in establishing the diagnosis if samples taken from all four quadrants with “extra passes in the antigravity areas are attempted.” 270 In some patients with the classical clinical appearance of IBC, tumor may not be found in biopsy samples from the skin, even if serial sections of the specimen are prepa red. 235,236,237,269 In one study, the skin biopsy specimen was reportedly negative in 50% of IBC patients. 236 Thus, no pat­ tern of histologic findings is specifically associated with the clinical diagnosis of primary IBC. “Inflammatory recurrent carcinoma” (secondary inflam­ matory carcinoma) is usually accompanied by nodules and plaques of invasive carcinoma in the dermis of the skin, as well as intralymphatic tumor emboli (Fig. 33.36). In some of these cases lymphatic tumor emboli are inconspicuous or not detectable. Clinically, erythema and edema occur equally in the skin over and around palpable dermal tumor infiltrates, regardless of the presence of dermal lymphatic tumor emboli. A review of the primary lesions in patients who developed an inflammatory recurrence suggested some predisposing features. 234 All patients initially had primary infiltrating duct carcinomas, including a disproportionately high number with apocrine cytology. Inflammatory recurrence was rarely found following treatment of papillary, medullary, and mu­ cinous carcinomas. Although these patients did not exhibit