During pregnancy and lactation, the breast can be affected by a variety of specific and unique disorders, including benign disorders closely related to physiologic changes, inflammatory and infectious diseases, juvenile papillomatosis, and benign and malignant tumors. Patients with pregnancy-associated breast carcinoma tend to have more advanced neoplasms at diagnosis and a poorer prognosis due to delayed diagnosis and a more aggressive biologic pattern. Pregnancy-related Burkitt lymphoma characteristically manifests with bilateral and diffuse involvement of the breasts. Fibroadenoma may manifest with growth, infarction, large cysts, prominent ducts, and secretory hyperplasia during pregnancy and lactation. Galactocele is the breast lesion most commonly found during lactation and manifests as either pseudolipoma, a cystic mass with a fat-fluid level, or pseudohamartoma. Tumors and diseases affecting the breasts during pregnancy and lactation are basically the same as those observed in nonpregnant women but may have a different appearance. The sensitivity of mammography in pregnant and lactating women is decreased due to increased parenchymal density. Instead, ultrasonography is the most appropriate radiologic method for evaluating breast masses in this setting and is particularly useful in the diagnosis and treatment of abscesses. Knowledge of the unique entities that are specifically related to pregnancy and lactation and of their radiologic-pathologic appearances can help the radiologist make the correct diagnosis.

The radiologic features of breast lesions caused by immunologic, reactive, and noncurrent infectious diseases often mimic those of malignancy, frequently constituting a diagnostic challenge even if the underlying disease is known. Churg-Strauss syndrome mimics carcinomatous mastitis. Amyloidosis usually manifests as a suspicious mass, often accompanied by microcalcifications. Wegener granulomatosis and sarcoidosis often manifest as irregular masses, although sarcoidosis can also manifest as round, well-defined masses reflecting intramammary node involvement. Diabetic mastopathy is a rare but well-known entity in patients with long-standing insulin-dependent diabetes. Breast involvement by necrobiotic xanthogranulomatosis is rare and manifests as multiple bilateral asymmetric lesions. Multiple clustered hypoechoic tubular structures in a large hypoechoic mass seen after pregnancy can be suggestive of granulomatous mastitis. Mammary tuberculosis can manifest with a nodular, diffuse, or sclerosing pattern. A granulomatous inflammatory reaction must be carefully evaluated because it constitutes the major feature of a diverse group of diseases that includes vasculitis, granulomatous mastitis, tuberculosis, and carcinoma-associated sarcoidlike reactions. Core biopsy can play a major role in developing a differential diagnosis for these rare immunologic, inflammatory, or infectious disorders affecting the breast, and knowledge of these entities can, in the appropriate clinical setting, help the radiologist narrow the differential diagnosis, although cancer must be excluded definitively.

Various mechanisms are thought to control excitation of pyramidal cells of the cerebral cortex. With immunocytochemical methods, we found that the proximal portions of numerous pyramidal cell axons (Pyr-axons) in the human and monkey neocortex are immunoreactive for the serotonin (5-HT) receptor 5-HT-(1A). With double-labeling experiments and confocal laser microscopy, we found that most (93.4%) of the 5-HT(1A)-immunoreactive Pyr-axons present in layers II and III were innervated by parvalbumin-immunoreactive chandelier cell axon terminals. In addition, Pyr-axons were compartmentalized: 5-HT-(1A) receptors were found proximal to inputs from chandelier cells. Although we found close appositions between GABAergic chandelier cell axon terminals and Pyr-axons, suggesting synaptic connections, we did not observe 5-HT-immunoreactive fibers in close proximity to the Pyr-axons. These results suggested that Pyr-axons are under the influence of 5-HT in a paracrine manner (via 5-HT-(1A) receptors) and, more distally, are under the influence of gamma-aminobutyric acid (GABA) in a synaptic manner (through the axons of chandelier cells). The local axonal specialization might represent a powerful inhibitory mechanism by which the responses of large populations of pyramidal cells can be globally controlled by subcortical serotonin afferents, in addition to local inputs from GABAergic interneurons.

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Lupus panniculitis is an unusual immunological disease that characteristically affects the subcutaneous fat and occurs in 2% of patients with systemic lupus erythematosus. We report a case of lupus panniculitis involving the breast, which represents a very uncommon location. Mammographically, it presented as a suspicious irregular mass involving the subcutaneous fat pad with skin thickening. High echogenicity constituted the most relevant sonographic finding. To the best of our knowledge, the magnetic resonance (MR) features have not been previously described. High signal intensity was found on both T1- and T2-weighted precontrast MR images. A dynamic contrast-enhanced study revealed a suspicious focal mass with irregular margins and rim enhancement, with a type 3 time-signal intensity curve. Differential diagnosis with carcinoma and fat necrosis and the value of core biopsy are discussed.