Protein kinase A regulates sperm motility through the cAMP-dependent phosphorylation of proteins. One mechanism to direct the activity of the kinase is to localize it near its protein substrates through the use of anchoring proteins. A-Kinase anchoring proteins (AKAPs) act by binding the type II regulatory subunit of protein kinase A and tethering it to a cellular organelle or cytoskeletal element. We showed previously that mAKAP82, the major protein of the fibrous sheath of the mouse sperm flagellum, is an AKAP. The available evidence indicates that protein kinase A is compartmentalized to the fibrous sheath by binding mAKAP82. To characterize AKAP82 in bovine sperm, a testicular cDNA library was constructed and used to isolate a clone encoding bAKAP82, the bovine homologue. Sequence analysis showed that the primary structure of bAKAP82 was highly conserved. In particular, the amino acid sequence corresponding to the region of mAKAP82 responsible for binding the regulatory subunit of protein kinase A was identical in the bull. Bovine AKAP82 was present in both epididymal and ejaculated sperm and was localized to the entire principal piece of the flagellum, the region in which the fibrous sheath is located. Finally, bAKAP82 bound the regulatory subunit of protein kinase A. These data support the idea that bAKAP82 functions as an anchoring protein for the subcellular localization of protein kinase A in the flagellum.

The term ‘Langerhans cell microgranuloma’ (LCM) was introduced a decade ago to draw attention to focal collections of these cells within the epidermal layer that develops during certain immune reactions. In spite of a growing awareness of this phenomenon during the past decade, few reports have focused on the development and phenotype of LCM. In this commentary, we review the historical development of the concept of LCM, demonstrate the salient immunomorphologic characteristics of LCM, and advance a hypothesis to explain their sequential evolution and formation.

A 77‐year‐old white female presented with a two to three year history of an asymptomatic skin‐colored papule on the right upper arm. Examination revealed a 7 mm × 7 mm soft papule, supplanted by a smaller soft papule. Clinical differential diagnosis included an adnexal tumor, neurofibroma, and dermal nevus. Histological examination revealed a sparse proliferation of spindle and stellate‐shaped cells within the dermis, including many large cells with bizarre shaped nuclei. Focal multinucleated giant cells were present as well. The background stroma was both collagenous and myxoid, the later being highlighted by diffuse colloidal iron staining. The spindle and stellate‐shaped cells demonstrated CD34 and vimentin positivity. Factor XIIIa was focally positive. Actin and S‐100 staining were negative. These changes were thought to be consistent with a myxoid pleomorphic fibroma. This is a rare tumor, with only a few reported cases of myxoid variants in the literature to date. The staining pattern of this tumor, along with others in the reported literature, suggest a mesenchymal, fibroblastic origin.