HUMAN PATHOLOGY
Volume 22, No. 11 (November
munoreactivity with the P-l 70 glycoprotein antibody JSB-1. No immunoreactivity was found in medullar cells. Most adrenal cortical cells also showed strong cytoplasmatic immunoreactivity with the JSB-1 antibody on frozen and paraffin sections. None of the medullar cells or negative control sections were immunoreactive. In our opinion, cytoplasmatic immunoreactivity could be related to P-170 glycoprotein as indicated by the immunoreactivity found in human adrenal cortical cells. The absence of staining in the medulla strengthens this opinion. However, one must bear in mind that most monoclonal antibodies directed against P-l 70 glycoprotein are not yet fully characterized with respect to their antigen recognition pattern, and some do not distinguish between the gene product of the MDR-2 gene, which is not related to multidrug resistance, and the gene product of the MDR-1 gene, P-l 70 glycoprotein.4 Whether cytoplasmatic immunoreactivity reflects “expression” of P-l 70 glycoprotein or is merely a crossreactivity with unknown antigens remains an open question.
E. VAN MAR(:K, MD, PHD University Hospital Antwerp Antwerp, Belgium
Pigmented
Adrenal Pheochromocytomas
To the Editor:-In response to a recently published article in HUMAN PATH~LWY regarding sympathoI would like to comment on adrenal paragangliomas,’ two adrenal pheochromocytomas that I encountered. Both tumors were functional, sporadic, benign pheochromocytomas found in middle-aged patients. Microscopically, one contained a focal area composed of spindle-shaped cells (very reminiscent of Schwann cells) that was very heavily pigmented with melanin. The remainder of the tumor was devoid of pigment. The second case was a classic pheochromocytoma histologically, with the typical, large polygonal cells containing large amounts of cytoplasmic melanin. In both cases, a Masson-Fontana stain for melanin and bleaching with picric acid confirmed melanin pigment. The occurrence of melanin within pheochromocytomas can be ascribed to the neural crest origin of both melanocytes and chromaffin cells of the adrenal gland. RUNJAN
BOOK REVIEWS
New York. NY, Chapman
3. Sugawara I, Nakahama M, Harx~ada H. et al: Apparent stnmrrer y extxes. GotI in the human adrenal cortex than it1the human adrenal medulla of Mr 170.000-180,000P-glyropt-otein.Gmrer Res 48:&l 14614. 1988 4. Grorgcs E. Brandley G. Gariepe J. et al: Detectiort of P-glycopn>tein isoforms by gene spPrifi
Volume 22, No. 11 (November
munoreactivity with the P-l 70 glycoprotein antibody JSB-1. No immunoreactivity was found in medullar cells. Most adrenal cortical cells also showed strong cytoplasmatic immunoreactivity with the JSB-1 antibody on frozen and paraffin sections. None of the medullar cells or negative control sections were immunoreactive. In our opinion, cytoplasmatic immunoreactivity could be related to P-170 glycoprotein as indicated by the immunoreactivity found in human adrenal cortical cells. The absence of staining in the medulla strengthens this opinion. However, one must bear in mind that most monoclonal antibodies directed against P-l 70 glycoprotein are not yet fully characterized with respect to their antigen recognition pattern, and some do not distinguish between the gene product of the MDR-2 gene, which is not related to multidrug resistance, and the gene product of the MDR-1 gene, P-l 70 glycoprotein.4 Whether cytoplasmatic immunoreactivity reflects “expression” of P-l 70 glycoprotein or is merely a crossreactivity with unknown antigens remains an open question.
E. VAN MAR(:K, MD, PHD University Hospital Antwerp Antwerp, Belgium
Pigmented
Adrenal Pheochromocytomas
To the Editor:-In response to a recently published article in HUMAN PATH~LWY regarding sympathoI would like to comment on adrenal paragangliomas,’ two adrenal pheochromocytomas that I encountered. Both tumors were functional, sporadic, benign pheochromocytomas found in middle-aged patients. Microscopically, one contained a focal area composed of spindle-shaped cells (very reminiscent of Schwann cells) that was very heavily pigmented with melanin. The remainder of the tumor was devoid of pigment. The second case was a classic pheochromocytoma histologically, with the typical, large polygonal cells containing large amounts of cytoplasmic melanin. In both cases, a Masson-Fontana stain for melanin and bleaching with picric acid confirmed melanin pigment. The occurrence of melanin within pheochromocytomas can be ascribed to the neural crest origin of both melanocytes and chromaffin cells of the adrenal gland. RUNJAN
BOOK REVIEWS
New York. NY, Chapman
3. Sugawara I, Nakahama M, Harx~ada H. et al: Apparent stnmrrer y extxes. GotI in the human adrenal cortex than it1the human adrenal medulla of Mr 170.000-180,000P-glyropt-otein.Gmrer Res 48:&l 14614. 1988 4. Grorgcs E. Brandley G. Gariepe J. et al: Detectiort of P-glycopn>tein isoforms by gene spPrifi
